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/* packet-x75.c
* Routines for X.75 frame disassembly
* Manawyrm <git@tbspace.de>
*
* based on lapb dissector by
* Olivier Abad <oabad@noos.fr>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <wiretap/wtap.h>
#include <epan/xdlc.h>
void proto_register_x75(void);
void proto_reg_handoff_x75(void);
#define X75_ADDRESS_SLP_STE_A 0x03
#define X75_ADDRESS_SLP_STE_B 0x01
#define X75_ADDRESS_MLP_STE_C 0x0F
#define X75_ADDRESS_MLP_STE_D 0x07
static int proto_x75 = -1;
static int hf_x75_address = -1;
static int hf_x75_control = -1;
static int hf_x75_n_r = -1;
static int hf_x75_n_s = -1;
static int hf_x75_p = -1;
static int hf_x75_f = -1;
static int hf_x75_s_ftype = -1;
static int hf_x75_u_modifier_cmd = -1;
static int hf_x75_u_modifier_resp = -1;
static int hf_x75_ftype_i = -1;
static int hf_x75_ftype_s_u = -1;
static gint ett_x75 = -1;
static gint ett_x75_control = -1;
static dissector_handle_t data_handle;
static dissector_handle_t x75_handle;
static const xdlc_cf_items x75_cf_items = {
&hf_x75_n_r,
&hf_x75_n_s,
&hf_x75_p,
&hf_x75_f,
&hf_x75_s_ftype,
&hf_x75_u_modifier_cmd,
&hf_x75_u_modifier_resp,
&hf_x75_ftype_i,
&hf_x75_ftype_s_u
};
static int
dissect_x75(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
proto_tree *x75_tree, *ti;
guint16 control;
int is_response;
guint8 byte0;
tvbuff_t *next_tvb;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "X.75");
col_set_str(pinfo->cinfo, COL_RES_NET_DST, "Broadcast");
byte0 = tvb_get_guint8(tvb, 0);
if (byte0 != X75_ADDRESS_SLP_STE_A && byte0 != X75_ADDRESS_SLP_STE_B &&
byte0 != X75_ADDRESS_MLP_STE_C && byte0 != X75_ADDRESS_MLP_STE_D) /* invalid X.75 frame */
{
col_set_str(pinfo->cinfo, COL_INFO, "Invalid X.75 frame");
if (tree)
proto_tree_add_protocol_format(tree, proto_x75, tvb, 0, -1,
"Invalid X.75 frame");
return 1;
}
// Clear lower layer src/dst address types, so our custom names
// are shown in the Packet List pane
pinfo->src.type = AT_NONE;
pinfo->dst.type = AT_NONE;
switch (pinfo->p2p_dir) {
case P2P_DIR_SENT:
if (byte0 == X75_ADDRESS_SLP_STE_A || byte0 == X75_ADDRESS_SLP_STE_B)
{
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "STE A");
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "STE B");
}
else
{
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "STE C");
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "STE D");
}
if (byte0 == X75_ADDRESS_SLP_STE_A || byte0 == X75_ADDRESS_MLP_STE_C)
is_response = TRUE;
else
is_response = FALSE;
break;
case P2P_DIR_RECV:
if (byte0 == X75_ADDRESS_SLP_STE_A || byte0 == X75_ADDRESS_SLP_STE_B)
{
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "STE B");
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "STE A");
}
else
{
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "STE D");
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "STE C");
}
if (byte0 == X75_ADDRESS_SLP_STE_B || byte0 == X75_ADDRESS_MLP_STE_D)
is_response = TRUE;
else
is_response = FALSE;
break;
default:
is_response = FALSE;
break;
}
if (is_response)
{
col_set_str(pinfo->cinfo, COL_PROTOCOL, "X.75 RSP");
}
else
{
col_set_str(pinfo->cinfo, COL_PROTOCOL, "X.75 CMD");
}
ti = proto_tree_add_protocol_format(tree, proto_x75, tvb, 0, 2,
"X.75");
x75_tree = proto_item_add_subtree(ti, ett_x75);
proto_tree_add_uint(x75_tree, hf_x75_address, tvb, 0, 1, byte0);
control = dissect_xdlc_control(tvb, 1, pinfo, x75_tree, hf_x75_control,
ett_x75_control, &x75_cf_items, NULL, NULL, NULL,
is_response, FALSE, FALSE);
/* information frame ==> data */
if (XDLC_IS_INFORMATION(control)) {
next_tvb = tvb_new_subset_remaining(tvb, 2);
int len = tvb_reported_length_remaining(next_tvb, 0);
// limit number of bytes being shown in COL_INFO
if (len > 128)
len = 128;
char *tmp = (char*)wmem_alloc(pinfo->pool, len + 1);
tmp[len] = 0x00;
tvb_memcpy(next_tvb, tmp, 0, len);
col_append_fstr(pinfo->cinfo, COL_INFO, ", %s", tmp);
wmem_free(pinfo->pool, tmp);
call_dissector(data_handle, next_tvb, pinfo, tree);
}
return tvb_captured_length(tvb);
}
void
proto_register_x75(void)
{
static hf_register_info hf[] = {
{ &hf_x75_address,
{ "Address", "x75.address", FT_UINT8, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_x75_control,
{ "Control Field", "x75.control", FT_UINT8, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_x75_n_r,
{ "N(R)", "x75.control.n_r", FT_UINT8, BASE_DEC,
NULL, XDLC_N_R_MASK, NULL, HFILL }},
{ &hf_x75_n_s,
{ "N(S)", "x75.control.n_s", FT_UINT8, BASE_DEC,
NULL, XDLC_N_S_MASK, NULL, HFILL }},
{ &hf_x75_p,
{ "Poll", "x75.control.p", FT_BOOLEAN, 8,
TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
{ &hf_x75_f,
{ "Final", "x75.control.f", FT_BOOLEAN, 8,
TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
{ &hf_x75_s_ftype,
{ "Supervisory frame type", "x75.control.s_ftype", FT_UINT8, BASE_HEX,
VALS(stype_vals), XDLC_S_FTYPE_MASK, NULL, HFILL }},
{ &hf_x75_u_modifier_cmd,
{ "Command", "x75.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
{ &hf_x75_u_modifier_resp,
{ "Response", "x75.control.u_modifier_resp", FT_UINT8, BASE_HEX,
VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
{ &hf_x75_ftype_i,
{ "Frame type", "x75.control.ftype", FT_UINT8, BASE_HEX,
VALS(ftype_vals), XDLC_I_MASK, NULL, HFILL }},
{ &hf_x75_ftype_s_u,
{ "Frame type", "x75.control.ftype", FT_UINT8, BASE_HEX,
VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
};
static gint *ett[] = {
&ett_x75,
&ett_x75_control,
};
proto_x75 = proto_register_protocol("Async data over ISDN (X.75)",
"X.75", "x75");
proto_register_field_array (proto_x75, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
x75_handle = register_dissector("x75", dissect_x75, proto_x75);
}
void
proto_reg_handoff_x75(void)
{
data_handle = find_dissector("data");
dissector_add_uint("wtap_encap", WTAP_ENCAP_LAPB, x75_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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