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wireshark/epan/dissectors/packet-mdshdr.c

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/* packet-mdshdr.c
* Routines for dissection of Cisco MDS Switch Internal Header
* Copyright 2001, Dinesh G Dutt <ddutt@andiamo.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/etypes.h>
#include <epan/prefs.h>
#include "packet-fc.h"
void proto_register_mdshdr(void);
void proto_reg_handoff_mdshdr(void);
#define MDSHDR_VERSION_OFFSET 0
/* Mdshdr Control bits */
#define MDSHDR_CTL_IDXDIRECT 1
#define MDSHDR_CTL_IGNACLO 2
#define MDSHDR_CTL_DRP 4
/* OFFSETS OF FIELDS */
#define MDSHDR_VER_OFFSET 0
#define MDSHDR_SOF_OFFSET 1
#define MDSHDR_PKTLEN_OFFSET 2
#define MDSHDR_DIDX_OFFSET 5
#define MDSHDR_SIDX_OFFSET 6
#define MDSHDR_VSAN_OFFSET 13
/* Two size definitions are sufficient */
#define MDSHDR_SIZE_BYTE sizeof(gchar)
#define MDSHDR_SIZE_INT16 sizeof(guint16)
#define MDSHDR_SIZE_INT32 sizeof(guint32)
/* Other miscellaneous defines; can't rely on sizeof structs */
#define MDSHDR_MAX_VERSION 0
#define MDSHDR_HEADER_SIZE 16
#define MDSHDR_TRAILER_SIZE 6
/* SOF Encodings */
#define MDSHDR_SOFc1 0x1
#define MDSHDR_SOFi1 0x2
#define MDSHDR_SOFn1 0x3
#define MDSHDR_SOFi2 0x4
#define MDSHDR_SOFn2 0x5
#define MDSHDR_SOFi3 0x6
#define MDSHDR_SOFn3 0x7
#define MDSHDR_SOFf 0x8
#define MDSHDR_SOFc4 0x9
#define MDSHDR_SOFi4 0xa
#define MDSHDR_SOFn4 0xb
/* EOF Encodings */
#define MDSHDR_EOFt 0x1
#define MDSHDR_EOFdt 0x2
#define MDSHDR_EOFa 0x4
#define MDSHDR_EOFn 0x3
#define MDSHDR_EOFdti 0x6
#define MDSHDR_EOFni 0x7
#define MDSHDR_EOFrt 0xa
#define MDSHDR_EOFrti 0xe
#define MDSHDR_EOF_UNKNOWN 0xb
/* Initialize the protocol and registered fields */
static int proto_mdshdr = -1;
static int hf_mdshdr_sof = -1;
static int hf_mdshdr_pkt_len = -1;
static int hf_mdshdr_dstidx = -1;
static int hf_mdshdr_srcidx = -1;
static int hf_mdshdr_vsan = -1;
static int hf_mdshdr_eof = -1;
static int hf_mdshdr_no_trailer = -1;
static int hf_mdshdr_span = -1;
static int hf_mdshdr_fccrc = -1;
/* Initialize the subtree pointers */
static gint ett_mdshdr = -1;
static gint ett_mdshdr_hdr = -1;
static gint ett_mdshdr_trlr = -1;
static dissector_handle_t fc_dissector_handle;
static gboolean decode_if_zero_etype = FALSE;
static const value_string sof_vals[] = {
{MDSHDR_SOFc1, "SOFc1"},
{MDSHDR_SOFi1, "SOFi1"},
{MDSHDR_SOFn1, "SOFn1"},
{MDSHDR_SOFi2, "SOFi2"},
{MDSHDR_SOFn2, "SOFn2"},
{MDSHDR_SOFi3, "SOFi3"},
{MDSHDR_SOFn3, "SOFn3"},
{MDSHDR_SOFc4, "SOFc4"},
{MDSHDR_SOFi4, "SOFi4"},
{MDSHDR_SOFn4, "SOFn4"},
{MDSHDR_SOFf, "SOFf"},
{0, NULL},
};
static const value_string eof_vals[] = {
{MDSHDR_EOFt, "EOFt"},
{MDSHDR_EOFdt, "EOFdt"},
{MDSHDR_EOFa, "EOFa"},
{MDSHDR_EOFn, "EOFn"},
{MDSHDR_EOFdti, "EOFdti"},
{MDSHDR_EOFni, "EOFni"},
{MDSHDR_EOFrt, "EOFrt"},
{MDSHDR_EOFrti, "EOFrti"},
/*{MDSHDR_EOF_UNKNOWN, ""}, intentionally removed*/
{0, NULL},
};
static int
dissect_mdshdr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
/* Set up structures needed to add the protocol subtree and manage it */
proto_item *ti_main;
proto_item *hidden_item;
proto_tree *mdshdr_tree_main, *mdshdr_tree_hdr, *mdshdr_tree_trlr;
int offset = 0;
guint pktlen;
tvbuff_t *next_tvb;
guint8 sof, eof;
int trailer_start = 0; /*0 means "no trailer found"*/
fc_data_t fc_data;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "MDS Header");
col_clear(pinfo->cinfo, COL_INFO);
sof = tvb_get_guint8(tvb, offset+MDSHDR_SOF_OFFSET) & 0x0F;
pktlen = tvb_get_ntohs(tvb, offset+MDSHDR_PKTLEN_OFFSET) & 0x1FFF;
/* The Mdshdr trailer is at the end of the frame */
if ((tvb_captured_length(tvb) >= (MDSHDR_HEADER_SIZE + pktlen))
/* Avoid header/trailer overlap if something wrong */
&& (pktlen >= MDSHDR_TRAILER_SIZE)) {
trailer_start = MDSHDR_HEADER_SIZE + pktlen - MDSHDR_TRAILER_SIZE;
eof = tvb_get_guint8(tvb, trailer_start);
tvb_set_reported_length(tvb, MDSHDR_HEADER_SIZE+pktlen);
}
else {
eof = MDSHDR_EOF_UNKNOWN;
}
fc_data.sof_eof = 0;
if ((sof == MDSHDR_SOFi3) || (sof == MDSHDR_SOFi2) || (sof == MDSHDR_SOFi1)
|| (sof == MDSHDR_SOFi4)) {
fc_data.sof_eof = FC_DATA_SOF_FIRST_FRAME;
}
else if (sof == MDSHDR_SOFf) {
fc_data.sof_eof = FC_DATA_SOF_SOFF;
}
if (eof != MDSHDR_EOFn) {
fc_data.sof_eof |= FC_DATA_EOF_LAST_FRAME;
}
else if (eof != MDSHDR_EOFt) {
fc_data.sof_eof |= FC_DATA_EOF_INVALID;
}
if (tree) {
ti_main = proto_tree_add_protocol_format(tree, proto_mdshdr, tvb, 0,
MDSHDR_HEADER_SIZE+pktlen,
"MDS Header(%s/%s)",
val_to_str(sof, sof_vals, "Unknown(%u)"),
val_to_str(eof, eof_vals, "Unknown(%u)"));
mdshdr_tree_main = proto_item_add_subtree(ti_main, ett_mdshdr);
/* Add Header part as subtree first */
mdshdr_tree_hdr = proto_tree_add_subtree(mdshdr_tree_main, tvb, MDSHDR_VER_OFFSET,
MDSHDR_HEADER_SIZE, ett_mdshdr_hdr, NULL, "MDS Header");
hidden_item = proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_sof, tvb, MDSHDR_SOF_OFFSET,
MDSHDR_SIZE_BYTE, ENC_BIG_ENDIAN);
proto_item_set_hidden(hidden_item);
proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_pkt_len, tvb, MDSHDR_PKTLEN_OFFSET,
MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_dstidx, tvb, MDSHDR_DIDX_OFFSET,
MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_srcidx, tvb, MDSHDR_SIDX_OFFSET,
MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_vsan, tvb, MDSHDR_VSAN_OFFSET,
MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
hidden_item = proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_span,
tvb, MDSHDR_VSAN_OFFSET,
MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
proto_item_set_hidden(hidden_item);
/* Add Mdshdr Trailer part */
if (tvb_reported_length(tvb) >= MDSHDR_HEADER_SIZE + pktlen
&& 0 != trailer_start) {
mdshdr_tree_trlr = proto_tree_add_subtree(mdshdr_tree_main, tvb, trailer_start,
MDSHDR_TRAILER_SIZE,
ett_mdshdr_trlr, NULL, "MDS Trailer");
proto_tree_add_item(mdshdr_tree_trlr, hf_mdshdr_eof, tvb,
trailer_start, MDSHDR_SIZE_BYTE, ENC_BIG_ENDIAN);
proto_tree_add_item(mdshdr_tree_trlr, hf_mdshdr_fccrc, tvb,
trailer_start+2, MDSHDR_SIZE_INT32, ENC_BIG_ENDIAN);
}
else {
proto_tree_add_item(mdshdr_tree_main, hf_mdshdr_no_trailer, tvb, 0, 0, ENC_NA);
}
}
if (tvb_reported_length(tvb) >= MDSHDR_HEADER_SIZE + pktlen
&& 0 != pktlen /*if something wrong*/) {
next_tvb = tvb_new_subset_length(tvb, MDSHDR_HEADER_SIZE, pktlen);
/* XXX what to do with the rest of this frame? --ArtemTamazov */
}
else {
next_tvb = tvb_new_subset_remaining(tvb, MDSHDR_HEADER_SIZE);
}
/* Call the Fibre Channel dissector */
if (fc_dissector_handle) {
fc_data.ethertype = ETHERTYPE_FCFT;
call_dissector_with_data(fc_dissector_handle, next_tvb, pinfo, tree, &fc_data);
}
else {
call_data_dissector(next_tvb, pinfo, tree);
}
return tvb_captured_length(tvb);
}
void
proto_register_mdshdr(void)
{
static hf_register_info hf[] = {
{ &hf_mdshdr_sof,
{"SOF", "mdshdr.sof", FT_UINT8, BASE_DEC, VALS(sof_vals), 0x0, NULL, HFILL}},
{ &hf_mdshdr_pkt_len,
{"Packet Len", "mdshdr.plen", FT_UINT16, BASE_DEC, NULL, 0x1FFF, NULL, HFILL}},
{ &hf_mdshdr_dstidx,
{"Dst Index", "mdshdr.dstidx", FT_UINT16, BASE_HEX, NULL, 0xFFC, NULL, HFILL}},
{ &hf_mdshdr_srcidx,
{"Src Index", "mdshdr.srcidx", FT_UINT16, BASE_HEX, NULL, 0x3FF, NULL, HFILL}},
{ &hf_mdshdr_vsan,
{"VSAN", "mdshdr.vsan", FT_UINT16, BASE_DEC, NULL, 0x0FFF, NULL, HFILL}},
{ &hf_mdshdr_eof,
{"EOF", "mdshdr.eof", FT_UINT8, BASE_DEC, VALS(eof_vals), 0x0, NULL, HFILL}},
{ &hf_mdshdr_no_trailer,
{"MDS Trailer: Not Found", "mdshdr.no_trailer", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL}},
{ &hf_mdshdr_span,
{"SPAN Frame", "mdshdr.span", FT_UINT16, BASE_DEC, NULL, 0xF000, NULL, HFILL}},
{ &hf_mdshdr_fccrc,
{"CRC", "mdshdr.crc", FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL}},
};
/* Setup protocol subtree array */
static gint *ett[] = {
&ett_mdshdr,
&ett_mdshdr_hdr,
&ett_mdshdr_trlr
};
module_t *mdshdr_module;
/* Register the protocol name and description */
proto_mdshdr = proto_register_protocol("MDS Header", "MDS Header", "mdshdr");
proto_register_field_array(proto_mdshdr, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
mdshdr_module = prefs_register_protocol(proto_mdshdr, proto_reg_handoff_mdshdr);
prefs_register_bool_preference(mdshdr_module, "decode_if_etype_zero",
"Decode as MDS Header if Ethertype == 0",
"A frame is considered for decoding as MDSHDR if either "
"ethertype is 0xFCFC or zero. Turn this flag off if you "
"don't want ethertype zero to be decoded as MDSHDR. "
"This might be useful to avoid problems with test frames.",
&decode_if_zero_etype);
}
void
proto_reg_handoff_mdshdr(void)
{
static dissector_handle_t mdshdr_handle;
static gboolean registered_for_zero_etype = FALSE;
static gboolean mdshdr_prefs_initialized = FALSE;
if (!mdshdr_prefs_initialized) {
/*
* This is the first time this has been called (i.e.,
* Wireshark/TShark is starting up), so create a handle for
* the MDS Header dissector, register the dissector for
* ethertype ETHERTYPE_FCFT, and fetch the data and Fibre
* Channel handles.
*/
mdshdr_handle = create_dissector_handle(dissect_mdshdr, proto_mdshdr);
dissector_add_uint("ethertype", ETHERTYPE_FCFT, mdshdr_handle);
fc_dissector_handle = find_dissector_add_dependency("fc", proto_mdshdr);
mdshdr_prefs_initialized = TRUE;
}
/*
* Only register the dissector for ethertype 0 if the preference
* is set to do so.
*/
if (decode_if_zero_etype) {
/*
* The preference to register for ethertype ETHERTYPE_UNK (0)
* is set; if we're not registered for ethertype ETHERTYPE_UNK,
* do so.
*/
if (!registered_for_zero_etype) {
dissector_add_uint("ethertype", ETHERTYPE_UNK, mdshdr_handle);
registered_for_zero_etype = TRUE;
}
} else {
/*
* The preference to register for ethertype ETHERTYPE_UNK (0)
* is not set; if we're registered for ethertype ETHERTYPE_UNK,
* undo that registration.
*/
if (registered_for_zero_etype) {
dissector_delete_uint("ethertype", ETHERTYPE_UNK, mdshdr_handle);
registered_for_zero_etype = FALSE;
}
}
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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