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wireshark/epan/dissectors/packet-v5dl.c

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/* packet-v5dl.c
* Routines for V5 data link frame disassembly
* Rolf Fiedler <rolf.fiedler@innoventif.de> using the LAPD code of
* Gilbert Ramirez <gram@alumni.rice.edu>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* V5 Data Link Layer
*
* V5 references:
* ETS 300 324-1
* ETS 300 347-1
*
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/xdlc.h>
void proto_register_v5dl(void);
static int proto_v5dl = -1;
static int hf_v5dl_direction = -1;
/* static int hf_v5dl_address = -1; */
static int hf_v5dl_ef = -1;
static int hf_v5dl_eah = -1;
static int hf_v5dl_cr = -1;
static int hf_v5dl_ea1 = -1;
static int hf_v5dl_eal = -1;
static int hf_v5dl_ea2 = -1;
static int hf_v5dl_control = -1;
static int hf_v5dl_n_r = -1;
static int hf_v5dl_n_s = -1;
static int hf_v5dl_p = -1;
static int hf_v5dl_p_ext = -1;
static int hf_v5dl_f = -1;
static int hf_v5dl_f_ext = -1;
static int hf_v5dl_s_ftype = -1;
static int hf_v5dl_u_modifier_cmd = -1;
static int hf_v5dl_u_modifier_resp = -1;
static int hf_v5dl_ftype_i = -1;
static int hf_v5dl_ftype_s_u = -1;
static int hf_v5dl_ftype_s_u_ext = -1;
#if 0
static int hf_v5dl_checksum = -1;
static int hf_v5dl_checksum_status = -1;
#endif
static gint ett_v5dl = -1;
static gint ett_v5dl_address = -1;
static gint ett_v5dl_control = -1;
/* static gint ett_v5dl_checksum = -1; */
static expert_field ei_v5dl_checksum = EI_INIT;
static dissector_handle_t v52_handle;
/*
* Bits in the address field.
*/
#define V5DL_EAH 0xfc00 /* Service Access Point Identifier */
#define V5DL_EAH_SHIFT 10
#define V5DL_CR 0x0200 /* Command/Response bit */
#define V5DL_EA1 0x0100 /* First Address Extension bit */
#define V5DL_EAL 0x00fe /* Terminal Endpoint Identifier */
#define V5DL_EAL_SHIFT 1
#define V5DL_EA2 0x0001 /* Second Address Extension bit */
static const value_string v5dl_direction_vals[] = {
{ P2P_DIR_RECV, "Network->User"},
{ P2P_DIR_SENT, "User->Network"},
{ 0, NULL }
};
static const value_string v5dl_addr_vals[] = {
{ 8175, "ISDN Protocol" },
{ 8176, "PSTN Protocol" },
{ 8177, "CONTROL Protocol" },
{ 8178, "BCC Protocol" },
{ 8179, "PROT Protocol" },
{ 8180, "Link Control Protocol" },
{ 8191, "VALUE RESERVED" },
{ 0, NULL } };
/* Used only for U frames */
static const xdlc_cf_items v5dl_cf_items = {
NULL,
NULL,
&hf_v5dl_p,
&hf_v5dl_f,
NULL,
&hf_v5dl_u_modifier_cmd,
&hf_v5dl_u_modifier_resp,
NULL,
&hf_v5dl_ftype_s_u
};
/* Used only for I and S frames */
static const xdlc_cf_items v5dl_cf_items_ext = {
&hf_v5dl_n_r,
&hf_v5dl_n_s,
&hf_v5dl_p_ext,
&hf_v5dl_f_ext,
&hf_v5dl_s_ftype,
NULL,
NULL,
&hf_v5dl_ftype_i,
&hf_v5dl_ftype_s_u_ext
};
#define MAX_V5DL_PACKET_LEN 1024
static int
dissect_v5dl(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
proto_tree *v5dl_tree, *addr_tree;
proto_item *v5dl_ti, *addr_ti;
int direction;
guint v5dl_header_len;
guint16 control;
#if 0
proto_tree *checksum_tree;
proto_item *checksum_ti;
guint16 checksum, checksum_calculated;
guint checksum_offset;
#endif
guint16 addr, cr, eah, eal, v5addr;
gboolean is_response = 0;
#if 0
guint length, reported_length;
#endif
tvbuff_t *next_tvb;
const char *srcname = "?";
const char *dstname = "?";
col_set_str(pinfo->cinfo, COL_PROTOCOL, "V5DL");
col_clear(pinfo->cinfo, COL_INFO);
addr = tvb_get_ntohs(tvb, 0);
cr = addr & V5DL_CR;
eal = (addr & V5DL_EAL) >> V5DL_EAL_SHIFT;
eah = (addr & V5DL_EAH) >> V5DL_EAH_SHIFT;
v5addr = (eah << 7) + eal;
v5dl_header_len = 2; /* addr */
direction = pinfo->p2p_dir;
if (pinfo->p2p_dir == P2P_DIR_RECV) {
is_response = cr ? FALSE : TRUE;
srcname = "Network";
dstname = "User";
}
else if (pinfo->p2p_dir == P2P_DIR_SENT) {
is_response = cr ? TRUE : FALSE;
srcname = "User";
dstname = "Network";
}
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, srcname);
col_set_str(pinfo->cinfo, COL_RES_DL_DST, dstname);
if (tree) {
proto_item *direction_ti;
v5dl_ti = proto_tree_add_item(tree, proto_v5dl, tvb, 0, -1,
ENC_NA);
v5dl_tree = proto_item_add_subtree(v5dl_ti, ett_v5dl);
/*
* Don't show the direction if we don't know it.
*/
if (direction != P2P_DIR_UNKNOWN) {
direction_ti = proto_tree_add_uint(v5dl_tree, hf_v5dl_direction,
tvb, 0, 0, pinfo->p2p_dir);
proto_item_set_generated(direction_ti);
}
addr_ti = proto_tree_add_uint(v5dl_tree, hf_v5dl_ef, tvb,
0, 2, v5addr);
addr_tree = proto_item_add_subtree(addr_ti, ett_v5dl_address);
proto_tree_add_uint(addr_tree, hf_v5dl_eah, tvb, 0, 1, addr);
proto_tree_add_uint(addr_tree, hf_v5dl_cr, tvb, 0, 1, addr);
proto_tree_add_uint(addr_tree, hf_v5dl_ea1, tvb, 0, 1, addr);
proto_tree_add_uint(addr_tree, hf_v5dl_eal, tvb, 1, 1, addr);
proto_tree_add_uint(addr_tree, hf_v5dl_ea2, tvb, 1, 1, addr);
}
else {
v5dl_ti = NULL;
v5dl_tree = NULL;
}
control = dissect_xdlc_control(tvb, 2, pinfo, v5dl_tree, hf_v5dl_control,
ett_v5dl_control, &v5dl_cf_items, &v5dl_cf_items_ext, NULL, NULL,
is_response, TRUE, FALSE);
v5dl_header_len += XDLC_CONTROL_LEN(control, TRUE);
if (tree)
proto_item_set_len(v5dl_ti, v5dl_header_len);
/*
* XXX - the sample capture supplied with bug 7027 does not
* appear to include checksums in the packets.
*/
#if 0
/*
* Check the checksum, if available.
* The checksum is a CCITT CRC-16 at the end of the packet, so
* if we don't have the entire packet in the capture - i.e., if
* tvb_captured_length(tvb) != tvb_reported_length(tvb) we can't check it.
*/
length = tvb_captured_length(tvb);
reported_length = tvb_reported_length(tvb);
/*
* If the reported length isn't big enough for the V5DL header
* and 2 bytes of checksum, the packet is malformed, as the
* checksum overlaps the header.
*/
if (reported_length < v5dl_header_len + 2)
return;
if (length == reported_length) {
/*
* There's no snapshot length cutting off any of the
* packet.
*/
checksum_offset = reported_length - 2;
checksum_calculated = crc16_ccitt_tvb(tvb, checksum_offset);
checksum_calculated = g_htons(checksum_calculated); /* Note: g_htons() macro may eval arg multiple times */
proto_tree_add_checksum(v5dl_tree, tvb, checksum_offset, hf_v5dl_checksum, hf_v5dl_checksum_status, &ei_v5dl_checksum,
pinfo, checksum_calculated, ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY);
/*
* Remove the V5DL header *and* the checksum.
*/
next_tvb = tvb_new_subset_length_caplen(tvb, v5dl_header_len,
tvb_captured_length_remaining(tvb, v5dl_header_len) - 2,
tvb_reported_length_remaining(tvb, v5dl_header_len) - 2);
} else {
/*
* Some or all of the packet is cut off by a snapshot
* length.
*/
if (length == reported_length - 1) {
/*
* One byte is cut off, so there's only one
* byte of checksum in the captured data.
* Remove that byte from the captured length
* and both bytes from the reported length.
*/
next_tvb = tvb_new_subset_length_caplen(tvb, v5dl_header_len,
tvb_captured_length_remaining(tvb, v5dl_header_len) - 1,
tvb_reported_length_remaining(tvb, v5dl_header_len) - 2);
} else {
/*
* Two or more bytes are cut off, so there are
* no bytes of checksum in the captured data.
* Just remove the checksum from the reported
* length.
*/
next_tvb = tvb_new_subset_length_caplen(tvb, v5dl_header_len,
tvb_captured_length_remaining(tvb, v5dl_header_len),
tvb_reported_length_remaining(tvb, v5dl_header_len) - 2);
}
}
#else
next_tvb = tvb_new_subset_remaining(tvb, v5dl_header_len);
#endif
if (XDLC_IS_INFORMATION(control)) {
/* call V5.2 dissector */
call_dissector(v52_handle, next_tvb, pinfo, tree);
}
return tvb_captured_length(tvb);
}
void
proto_reg_handoff_v5dl(void);
void
proto_register_v5dl(void)
{
static hf_register_info hf[] = {
{ &hf_v5dl_direction,
{ "Direction", "v5dl.direction", FT_UINT8, BASE_DEC, VALS(v5dl_direction_vals), 0x0,
NULL, HFILL }},
#if 0
{ &hf_v5dl_address,
{ "Address Field", "v5dl.address", FT_UINT16, BASE_HEX, NULL, 0x0,
"Address", HFILL }},
#endif
{ &hf_v5dl_ef,
{ "EF", "v5dl.ef", FT_UINT16, BASE_DEC, VALS(v5dl_addr_vals), 0x0,
"Envelope Function Address", HFILL }},
{ &hf_v5dl_eah,
{ "EAH", "v5dl.eah", FT_UINT16, BASE_DEC, NULL, V5DL_EAH,
"Envelope Address High", HFILL }},
{ &hf_v5dl_cr,
{ "C/R", "v5dl.cr", FT_UINT16, BASE_DEC, NULL, V5DL_CR,
"Command/Response bit", HFILL }},
{ &hf_v5dl_ea1,
{ "EA1", "v5dl.ea1", FT_UINT16, BASE_DEC, NULL, V5DL_EA1,
"First Address Extension bit", HFILL }},
{ &hf_v5dl_eal,
{ "EAL", "v5dl.eal", FT_UINT16, BASE_DEC, NULL, V5DL_EAL,
"Envelope Address Low", HFILL }},
{ &hf_v5dl_ea2,
{ "EA2", "v5dl.ea2", FT_UINT16, BASE_DEC, NULL, V5DL_EA2,
"Second Address Extension bit", HFILL }},
{ &hf_v5dl_control,
{ "Control Field", "v5dl.control", FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_v5dl_n_r,
{ "N(R)", "v5dl.control.n_r", FT_UINT16, BASE_DEC,
NULL, XDLC_N_R_EXT_MASK, NULL, HFILL }},
{ &hf_v5dl_n_s,
{ "N(S)", "v5dl.control.n_s", FT_UINT16, BASE_DEC,
NULL, XDLC_N_S_EXT_MASK, NULL, HFILL }},
{ &hf_v5dl_p,
{ "Poll", "v5dl.control.p", FT_BOOLEAN, 8,
TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
{ &hf_v5dl_p_ext,
{ "Poll", "v5dl.control.p", FT_BOOLEAN, 16,
TFS(&tfs_set_notset), XDLC_P_F_EXT, NULL, HFILL }},
{ &hf_v5dl_f,
{ "Final", "v5dl.control.f", FT_BOOLEAN, 8,
TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
{ &hf_v5dl_f_ext,
{ "Final", "v5dl.control.f", FT_BOOLEAN, 16,
TFS(&tfs_set_notset), XDLC_P_F_EXT, NULL, HFILL }},
{ &hf_v5dl_s_ftype,
{ "Supervisory frame type", "v5dl.control.s_ftype", FT_UINT16, BASE_HEX,
VALS(stype_vals), XDLC_S_FTYPE_MASK, NULL, HFILL }},
{ &hf_v5dl_u_modifier_cmd,
{ "Command", "v5dl.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
{ &hf_v5dl_u_modifier_resp,
{ "Response", "v5dl.control.u_modifier_resp", FT_UINT8, BASE_HEX,
VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
{ &hf_v5dl_ftype_i,
{ "Frame type", "v5dl.control.ftype", FT_UINT16, BASE_HEX,
VALS(ftype_vals), XDLC_I_MASK, NULL, HFILL }},
{ &hf_v5dl_ftype_s_u,
{ "Frame type", "v5dl.control.ftype", FT_UINT8, BASE_HEX,
VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
{ &hf_v5dl_ftype_s_u_ext,
{ "Frame type", "v5dl.control.ftype", FT_UINT16, BASE_HEX,
VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
#if 0
{ &hf_v5dl_checksum,
{ "Checksum", "v5dl.checksum", FT_UINT16, BASE_HEX,
NULL, 0x0, "Details at: https://www.wireshark.org/docs/wsug_html_chunked/ChAdvChecksums.html", HFILL }},
{ &hf_v5dl_checksum_status,
{ "Checksum Status", "v5dl.checksum.status", FT_UINT8, BASE_NONE,
VALS(proto_checksum_vals), 0x0, NULL, HFILL }},
#endif
};
static gint *ett[] = {
&ett_v5dl,
&ett_v5dl_address,
&ett_v5dl_control,
/* &ett_v5dl_checksum */
};
static ei_register_info ei[] = {
{ &ei_v5dl_checksum, { "v5dl.bad_checksum", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }},
};
expert_module_t* expert_v5dl;
proto_v5dl = proto_register_protocol("V5 Data Link Layer", "V5DL", "v5dl");
proto_register_field_array (proto_v5dl, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_v5dl = expert_register_protocol(proto_v5dl);
expert_register_field_array(expert_v5dl, ei, array_length(ei));
register_dissector("v5dl", dissect_v5dl, proto_v5dl);
}
void
proto_reg_handoff_v5dl(void)
{
v52_handle = find_dissector_add_dependency("v52", proto_v5dl);
}
/*
* 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:
*/
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