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wireshark/epan/dissectors/packet-cesoeth.c

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/* packet-cesoeth.c
* Dissection of Circuit Emulation Service over Ethernet (MEF 8)
* www.mef.net
*
* Copyright 2018, AimValley B.V.
* Jaap Keuter <jkeuter@aimvalley.nl>
*
* 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/prefs.h>
#include <epan/expert.h>
#include <epan/etypes.h>
#include <epan/dissectors/packet-rtp.h>
void proto_register_cesoeth(void);
void proto_reg_handoff_cesoeth(void);
static int proto_cesoeth = -1;
static int hf_cesoeth_pw_ecid = -1;
static int hf_cesoeth_pw_res = -1;
static int hf_cesoeth_cw = -1;
static int hf_cesoeth_cw_reserved1 = -1;
static int hf_cesoeth_cw_l = -1;
static int hf_cesoeth_cw_r = -1;
static int hf_cesoeth_cw_l0_m = -1;
static int hf_cesoeth_cw_l1_m = -1;
static int hf_cesoeth_cw_frg = -1;
static int hf_cesoeth_cw_len = -1;
static int hf_cesoeth_cw_seq = -1;
static int hf_cesoeth_padding = -1;
static gint ett_cesoeth = -1;
static gint ett_cesoeth_cw = -1;
static expert_field ei_cesoeth_reserved = EI_INIT;
static expert_field ei_cesoeth_length = EI_INIT;
static int* const cesoeth_l0_cw[] =
{
&hf_cesoeth_cw_reserved1,
&hf_cesoeth_cw_l,
&hf_cesoeth_cw_r,
&hf_cesoeth_cw_l0_m,
&hf_cesoeth_cw_frg,
&hf_cesoeth_cw_len,
&hf_cesoeth_cw_seq,
NULL
};
static int* const cesoeth_l1_cw[] =
{
&hf_cesoeth_cw_reserved1,
&hf_cesoeth_cw_l,
&hf_cesoeth_cw_r,
&hf_cesoeth_cw_l1_m,
&hf_cesoeth_cw_frg,
&hf_cesoeth_cw_len,
&hf_cesoeth_cw_seq,
NULL
};
static const value_string frg_names[] =
{
{ 0, "No fragmentation" },
{ 1, "First fragment" },
{ 2, "Last fragment" },
{ 3, "Intermediate fragment" },
{ 0, NULL }
};
static const value_string l0_m_names[] =
{
{ 0, "No local TDM defect" },
{ 1, "Reserved" },
{ 2, "RDI on TDM input" },
{ 3, "Non-TDM data" },
{ 0, NULL }
};
static const value_string l1_m_names[] =
{
{ 0, "TDM defect" },
{ 1, "Reserved" },
{ 2, "Reserved" },
{ 3, "Reserved" },
{ 0, NULL }
};
/* Preferences */
static gboolean has_rtp_header = FALSE;
static gboolean heuristic_rtp_header = TRUE;
static int
dissect_cesoeth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
proto_tree *cesoeth_tree;
proto_item *cesoeth_ti;
proto_item *bitmask_ti;
int offset = 0;
guint32 ecid, reserved;
gboolean l_bit, r_bit;
guint8 m_bits, frg;
gint cw_len, padding_len, tail_len, payload_len;
guint16 sn;
tvbuff_t *next_tvb;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "CESoETH");
col_clear(pinfo->cinfo, COL_INFO);
cesoeth_ti = proto_tree_add_item(tree, proto_cesoeth, tvb, 0, -1, ENC_NA);
cesoeth_tree = proto_item_add_subtree(cesoeth_ti, ett_cesoeth);
proto_tree_add_item_ret_uint(cesoeth_tree, hf_cesoeth_pw_ecid, tvb, offset, 4, ENC_BIG_ENDIAN, &ecid);
col_append_fstr(pinfo->cinfo, COL_INFO, "ECID: 0x%05x", ecid);
bitmask_ti = proto_tree_add_item_ret_uint(cesoeth_tree, hf_cesoeth_pw_res, tvb, offset, 4, ENC_BIG_ENDIAN, &reserved);
if (reserved != 0x102)
expert_add_info_format(pinfo, bitmask_ti, &ei_cesoeth_reserved, "Reserved field must be 0x102");
offset += 4;
/*
* CES header control word
*
* bits name description
* 31-28 reserved set to 0
* 27 L-bit set to 1 to indicate local TDM failure
* 26 R-bit set to 1 to indicate remote loss of frame
* 25-24 M-bits modifier bits
* 23-22 FRG bits fragmentation bits
* 21-16 length length (0 if no padding applied)
* 15-0 sequence sequence number
*/
l_bit = (tvb_get_guint8(tvb, offset) & 0x08) ? TRUE : FALSE;
r_bit = (tvb_get_guint8(tvb, offset) & 0x04) ? TRUE : FALSE;
m_bits = (tvb_get_guint8(tvb, offset) & 0x03);
frg = tvb_get_bits8(tvb, 40, 2);
cw_len = tvb_get_bits8(tvb, 42, 6);
sn = tvb_get_ntohs(tvb, offset + 2);
col_append_fstr(pinfo->cinfo, COL_INFO, ", SN: %u", sn);
if (l_bit)
{
bitmask_ti = proto_tree_add_bitmask(cesoeth_tree, tvb, offset, hf_cesoeth_cw, ett_cesoeth_cw, cesoeth_l1_cw, ENC_NA);
col_append_sep_fstr(pinfo->cinfo, COL_INFO, NULL, "%s", val_to_str_const(m_bits, l1_m_names, "Unknown"));
} else {
bitmask_ti = proto_tree_add_bitmask(cesoeth_tree, tvb, offset, hf_cesoeth_cw, ett_cesoeth_cw, cesoeth_l0_cw, ENC_NA);
if (m_bits)
col_append_sep_fstr(pinfo->cinfo, COL_INFO, NULL, "%s", val_to_str_const(m_bits, l0_m_names, "Unknown"));
}
if (cw_len >= 42)
{
/*
* Now we have to go spelunking in the bitmask tree for the length item
* in order to add an expert item to it.
*/
proto_tree *bm_tree = proto_item_get_subtree(bitmask_ti);
if (bm_tree) {
proto_item *pi;
for (pi = tree->first_child; pi; pi = pi->next)
{
field_info *fi;
fi = PITEM_FINFO(pi);
if (fi && (fi->hfinfo->id == hf_cesoeth_cw_len))
break;
}
expert_add_info_format(pinfo, pi, &ei_cesoeth_length, "Length can not be 42 or larger");
}
cw_len = 0; /* Put a stop to this madness */
}
if (r_bit)
col_append_sep_str(pinfo->cinfo, COL_INFO, NULL, "Remote loss of frame");
if (frg)
col_append_sep_fstr(pinfo->cinfo, COL_INFO, NULL, "%s", val_to_str_const(frg, frg_names, "Unknown"));
offset += 4;
/*
* When L is set the TDM payload MAY be missing.
* But also when snap value is used on capture.
* Will the optional RTP header be there when the TDM payload is missing? I guess so.
* Length includes the size of the CW (being 4), the optional RTP header (being 12) and
* the TDM payload, as long as it doesn't exceed 42 octets. Length > 0 indicates padding,
* which must NOT be passed to the RTP dissector, it's not RTP padding.
*/
padding_len = (cw_len > 0) ? (42 - cw_len) : 0;
tail_len = tvb_reported_length_remaining(tvb, offset);
payload_len = tail_len - padding_len;
if (payload_len > 0)
{
next_tvb = tvb_new_subset_length(tvb, offset, payload_len);
if ((has_rtp_header) ||
((heuristic_rtp_header) &&
/* Check for RTP version 2, the other fields must be zero */
(tvb_get_guint8(tvb, offset) == 0x80) &&
/* Check the marker is zero. Unfortnately PT is not always from the dynamic range */
((tvb_get_guint8(tvb, offset + 1) & 0x80) == 0) &&
/* The sequence numbers from cw and RTP header must match */
(tvb_get_ntohs(tvb, offset + 2) == sn)))
{
struct _rtp_info rtp_info;
gint rtp_header_len = dissect_rtp_shim_header(tvb, offset, pinfo, cesoeth_tree, &rtp_info);
col_set_str(pinfo->cinfo, COL_PROTOCOL, "CESoETH (w RTP)");
col_append_sep_fstr(pinfo->cinfo, COL_INFO, NULL, "RTP PT: %u, SSRC: 0x%X, Seq: %u, Time=%u",
rtp_info.info_payload_type,
rtp_info.info_sync_src,
rtp_info.info_seq_num,
rtp_info.info_timestamp
);
next_tvb = tvb_new_subset_length(tvb, offset + rtp_header_len, payload_len - rtp_header_len);
}
call_data_dissector(next_tvb, pinfo, tree);
offset += payload_len;
}
if (padding_len > 0)
{
proto_tree_add_item(cesoeth_tree, hf_cesoeth_padding, tvb, offset, padding_len, ENC_NA);
offset += padding_len;
}
return offset;
}
void
proto_register_cesoeth(void)
{
static hf_register_info hf[] = {
{ &hf_cesoeth_pw_ecid,
{ "ECID", "cesoeth.ecid", FT_UINT32, BASE_HEX,
NULL, 0xFFFFF000, NULL, HFILL }},
{ &hf_cesoeth_pw_res,
{ "Reserved", "cesoeth.res", FT_UINT32, BASE_HEX,
NULL, 0x00000FFF, "Reserved (0x102)", HFILL }},
{ &hf_cesoeth_cw,
{ "Control word", "cesoeth.cw", FT_UINT32, BASE_HEX,
NULL, 0x0, NULL, HFILL }},
{ &hf_cesoeth_cw_reserved1,
{ "Reserved", "cesoeth.cw.reserved", FT_UINT32, BASE_HEX,
NULL, 0xF0000000, NULL, HFILL }},
{ &hf_cesoeth_cw_l,
{ "L-bit", "cesoeth.cw.l", FT_BOOLEAN, 32,
NULL, 0x08000000, "Local TDM failure", HFILL }},
{ &hf_cesoeth_cw_r,
{ "R-bit", "cesoeth.cw.r", FT_BOOLEAN, 32,
NULL, 0x04000000, "Remote Loss of Frames indication", HFILL }},
{ &hf_cesoeth_cw_l0_m,
{ "M-bits", "cesoeth.cw.m", FT_UINT32, BASE_HEX,
VALS(l0_m_names), 0x03000000, "Modifier bits", HFILL }},
{ &hf_cesoeth_cw_l1_m,
{ "M-bits", "cesoeth.cw.m", FT_UINT32, BASE_HEX,
VALS(l1_m_names), 0x03000000, "Modifier bits", HFILL }},
{ &hf_cesoeth_cw_frg,
{ "Frg", "cesoeth.cw.frg", FT_UINT32, BASE_HEX,
VALS(frg_names), 0x00C00000, "Fragmentation bits", HFILL }},
{ &hf_cesoeth_cw_len,
{ "Len", "cesoeth.cw.len", FT_UINT32, BASE_DEC,
NULL, 0x003F0000, "Length", HFILL }},
{ &hf_cesoeth_cw_seq,
{ "SN", "cesoeth.cw.sn", FT_UINT32, BASE_DEC,
NULL, 0x0000FFFF, "Sequence number", HFILL }},
{ &hf_cesoeth_padding,
{ "Padding", "cesoeth.padding", FT_BYTES, BASE_NONE,
NULL, 0x0, NULL, HFILL }}
};
static gint *ett[] = {
&ett_cesoeth,
&ett_cesoeth_cw
};
static ei_register_info ei[] = {
{ &ei_cesoeth_reserved,
{ "cesoeth.reserved", PI_PROTOCOL, PI_WARN,
"Reserved field", EXPFILL }},
{ &ei_cesoeth_length,
{ "cesoeth.length", PI_PROTOCOL, PI_WARN,
"Length field", EXPFILL }}
};
module_t *cesoeth_module;
expert_module_t* expert_cesoeth;
proto_cesoeth = proto_register_protocol("Circuit Emulation Service over Ethernet", "CESoETH", "cesoeth");
proto_register_field_array(proto_cesoeth, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_cesoeth = expert_register_protocol(proto_cesoeth);
expert_register_field_array(expert_cesoeth, ei, array_length(ei));
cesoeth_module = prefs_register_protocol(proto_cesoeth, NULL);
prefs_register_bool_preference(cesoeth_module, "rtp_header", "RTP header in CES payload",
"Whether or not the RTP header is present in the CES payload.", &has_rtp_header);
prefs_register_bool_preference(cesoeth_module, "rtp_header_heuristic", "Try to find RTP header in CES payload",
"Heuristically determine if an RTP header is present in the CES payload.", &heuristic_rtp_header);
}
void
proto_reg_handoff_cesoeth(void)
{
dissector_handle_t cesoeth_handle;
cesoeth_handle = create_dissector_handle(dissect_cesoeth, proto_cesoeth);
dissector_add_uint("ethertype", ETHERTYPE_CESOETH, cesoeth_handle);
}
/*
* 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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