/* packet-v120.c
 * Routines for v120 frame disassembly
 * Bert Driehuis <driehuis@playbeing.org>
 *
 * 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 <epan/xdlc.h>

void proto_register_v120(void);

static int proto_v120 = -1;
static int hf_v120_address = -1;
static int hf_v120_rc = -1;
static int hf_v120_lli = -1;
static int hf_v120_ea0 = -1;
static int hf_v120_ea1 = -1;
static int hf_v120_control = -1;
static int hf_v120_n_r = -1;
static int hf_v120_n_s = -1;
static int hf_v120_p = -1;
static int hf_v120_p_ext = -1;
static int hf_v120_f = -1;
static int hf_v120_f_ext = -1;
static int hf_v120_s_ftype = -1;
static int hf_v120_u_modifier_cmd = -1;
static int hf_v120_u_modifier_resp = -1;
static int hf_v120_ftype_i = -1;
static int hf_v120_ftype_s_u = -1;
static int hf_v120_ftype_s_u_ext = -1;
static int hf_v120_header8 = -1;
static int hf_v120_header_ext8 = -1;
static int hf_v120_header_break8 = -1;
static int hf_v120_header_error_control8 = -1;
static int hf_v120_header_segb8 = -1;
static int hf_v120_header_segf8 = -1;
static int hf_v120_header16 = -1;
static int hf_v120_header_ext16 = -1;
static int hf_v120_header_break16 = -1;
static int hf_v120_header_error_control16 = -1;
static int hf_v120_header_segb16 = -1;
static int hf_v120_header_segf16 = -1;
static int hf_v120_header_e = -1;
static int hf_v120_header_dr = -1;
static int hf_v120_header_sr = -1;
static int hf_v120_header_rr = -1;

static gint ett_v120 = -1;
static gint ett_v120_address = -1;
static gint ett_v120_control = -1;
static gint ett_v120_header = -1;

static int dissect_v120_header(tvbuff_t *tvb, int offset, proto_tree *tree);

/* Used only for U frames */
static const xdlc_cf_items v120_cf_items = {
	NULL,
	NULL,
	&hf_v120_p,
	&hf_v120_f,
	NULL,
	&hf_v120_u_modifier_cmd,
	&hf_v120_u_modifier_resp,
	NULL,
	&hf_v120_ftype_s_u
};

/* Used only for I and S frames */
static const xdlc_cf_items v120_cf_items_ext = {
	&hf_v120_n_r,
	&hf_v120_n_s,
	&hf_v120_p_ext,
	&hf_v120_f_ext,
	&hf_v120_s_ftype,
	NULL,
	NULL,
	&hf_v120_ftype_i,
	&hf_v120_ftype_s_u_ext
};

static int
dissect_v120(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
	proto_tree *v120_tree, *address_tree;
	proto_item *ti, *tc;
	int	    is_response;
	int	    v120len;
	guint8      byte0, byte1;
	guint16     control;
	tvbuff_t   *next_tvb;

	col_set_str(pinfo->cinfo, COL_PROTOCOL, "V.120");
	col_clear(pinfo->cinfo, COL_INFO);

	byte0 = tvb_get_guint8(tvb, 0);

	col_add_fstr(pinfo->cinfo, COL_RES_DL_SRC, "0x%02X", byte0);

	byte1 = tvb_get_guint8(tvb, 1);

	if ( ((byte0 & 0x01) != 0x00) && ((byte1 & 0x01) != 0x01) )
	{
		col_set_str(pinfo->cinfo, COL_INFO, "Invalid V.120 frame");
		if (tree)
			proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, -1,
									"Invalid V.120 frame");
		return 2;
	}

	if (pinfo->p2p_dir == P2P_DIR_SENT) {
		is_response = (byte0 & 0x02) ? FALSE: TRUE;
		col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
		col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE");
	} else {
		/* XXX - what if the direction is unknown? */
		is_response = (byte0 & 0x02) ? TRUE : FALSE;
		col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
		col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
	}

	ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, -1, "V.120");
	v120_tree = proto_item_add_subtree(ti, ett_v120);
	tc = proto_tree_add_item(v120_tree, hf_v120_address, tvb, 0, 2, ENC_BIG_ENDIAN);
	proto_item_append_text(tc, "LLI: %d C/R: %s",
			((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1),
			byte0 & 0x02 ? "R" : "C");
	address_tree = proto_item_add_subtree(tc, ett_v120_address);

	proto_tree_add_item(address_tree, hf_v120_rc, tvb, 0, 2, ENC_BIG_ENDIAN);
	proto_tree_add_item(address_tree, hf_v120_lli, tvb, 0, 2, ENC_BIG_ENDIAN);
	proto_tree_add_item(address_tree, hf_v120_ea0, tvb, 0, 2, ENC_BIG_ENDIAN);
	proto_tree_add_item(address_tree, hf_v120_ea1, tvb, 0, 2, ENC_BIG_ENDIAN);

	control = dissect_xdlc_control(tvb, 2, pinfo, v120_tree, hf_v120_control,
		ett_v120_control, &v120_cf_items, &v120_cf_items_ext,
		NULL, NULL, is_response, TRUE, FALSE);

	v120len = 2 + XDLC_CONTROL_LEN(control, TRUE);

	if (tvb_bytes_exist(tvb, v120len, 1))
		v120len += dissect_v120_header(tvb, v120len, v120_tree);
	proto_item_set_len(ti, v120len);
	next_tvb = tvb_new_subset_remaining(tvb, v120len);
	call_data_dissector(next_tvb, pinfo, v120_tree);

	return tvb_captured_length(tvb);
}

static int
dissect_v120_header(tvbuff_t *tvb, int offset, proto_tree *tree)
{
	int         header_len;
	guint8      byte0;
	proto_tree *h_tree;
	proto_item *tc;

	byte0 = tvb_get_guint8(tvb, offset);
	if (byte0 & 0x80) {
		header_len = 1;
		tc = proto_tree_add_item(tree, hf_v120_header8, tvb, 0, 1, ENC_BIG_ENDIAN);

		h_tree = proto_item_add_subtree(tc, ett_v120_header);
		proto_tree_add_item(h_tree, hf_v120_header_ext8, tvb, 0, 1, ENC_NA);
		proto_tree_add_item(h_tree, hf_v120_header_break8, tvb, 0, 1, ENC_NA);
		proto_tree_add_item(h_tree, hf_v120_header_error_control8, tvb, 0, 1, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_segb8, tvb, 0, 1, ENC_NA);
		proto_tree_add_item(h_tree, hf_v120_header_segf8, tvb, 0, 1, ENC_NA);
	} else {
		header_len = 2;
		tc = proto_tree_add_item(tree, hf_v120_header16, tvb, 0, 2, ENC_BIG_ENDIAN);
		h_tree = proto_item_add_subtree(tc, ett_v120_header);
		proto_tree_add_item(h_tree, hf_v120_header_ext16, tvb, 0, 2, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_break16, tvb, 0, 2, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_error_control16, tvb, 0, 2, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_segb16, tvb, 0, 2, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_segf16, tvb, 0, 2, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_e, tvb, 0, 2, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_dr, tvb, 0, 2, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_sr, tvb, 0, 2, ENC_BIG_ENDIAN);
		proto_tree_add_item(h_tree, hf_v120_header_rr, tvb, 0, 2, ENC_BIG_ENDIAN);
	}

	proto_item_append_text(tc, " B: %d F: %d",
			       byte0 & 0x02 ? 1:0, byte0 & 0x01 ? 1:0);

	return header_len;
}

void
proto_register_v120(void)
{
	static hf_register_info hf[] = {
		{ &hf_v120_address,
		  { "Link Address", "v120.address", FT_UINT16, BASE_HEX, NULL,
		    0x0, NULL, HFILL }},
		{ &hf_v120_rc,
		  { "R/C", "v120.rc", FT_BOOLEAN, 16, TFS(&tfs_response_command),
		    0x0002, NULL, HFILL }},
		{ &hf_v120_lli,
		  { "LLI", "v120.lli", FT_UINT16, BASE_HEX, NULL,
		    0xfefc, NULL, HFILL }},
		{ &hf_v120_ea0,
		  { "EA0", "v120.ea0", FT_BOOLEAN, 16, TFS(&tfs_error_ok),
		    0x0001, NULL, HFILL }},
		{ &hf_v120_ea1,
		  { "EA1", "v120.ea1", FT_BOOLEAN, 16, TFS(&tfs_ok_error),
		    0x0100, NULL, HFILL }},
		{ &hf_v120_control,
		  { "Control Field", "v120.control", FT_UINT16, BASE_HEX, NULL, 0x0,
		    NULL, HFILL }},
		{ &hf_v120_n_r,
		  { "N(R)", "v120.control.n_r", FT_UINT16, BASE_DEC,
		    NULL, XDLC_N_R_EXT_MASK, NULL, HFILL }},
		{ &hf_v120_n_s,
		  { "N(S)", "v120.control.n_s", FT_UINT16, BASE_DEC,
		    NULL, XDLC_N_S_EXT_MASK, NULL, HFILL }},
		{ &hf_v120_p,
		  { "Poll", "v120.control.p", FT_BOOLEAN, 8,
		    TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
		{ &hf_v120_p_ext,
		  { "Poll", "v120.control.p", FT_BOOLEAN, 16,
		    TFS(&tfs_set_notset), XDLC_P_F_EXT, NULL, HFILL }},
		{ &hf_v120_f,
		  { "Final", "v120.control.f", FT_BOOLEAN, 8,
		    TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
		{ &hf_v120_f_ext,
		  { "Final", "v120.control.f", FT_BOOLEAN, 16,
		    TFS(&tfs_set_notset), XDLC_P_F_EXT, NULL, HFILL }},
		{ &hf_v120_s_ftype,
		  { "Supervisory frame type", "v120.control.s_ftype", FT_UINT16, BASE_HEX,
		    VALS(stype_vals), XDLC_S_FTYPE_MASK, NULL, HFILL }},
		{ &hf_v120_u_modifier_cmd,
		  { "Command", "v120.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
		    VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
		{ &hf_v120_u_modifier_resp,
		  { "Response", "v120.control.u_modifier_resp", FT_UINT8, BASE_HEX,
		    VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
		{ &hf_v120_ftype_i,
		  { "Frame type", "v120.control.ftype", FT_UINT16, BASE_HEX,
		    VALS(ftype_vals), XDLC_I_MASK, NULL, HFILL }},
		{ &hf_v120_ftype_s_u,
		  { "Frame type", "v120.control.ftype", FT_UINT8, BASE_HEX,
		    VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
		{ &hf_v120_ftype_s_u_ext,
		  { "Frame type", "v120.control.ftype", FT_UINT16, BASE_HEX,
		    VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
		{ &hf_v120_header8,
		  { "Header", "v120.header", FT_UINT8, BASE_HEX, NULL, 0x0,
		    NULL, HFILL }},
		{ &hf_v120_header_ext8,
		  { "Extension octet", "v120.header.ext", FT_BOOLEAN, 8, TFS(&tfs_yes_no), 0x80,
		    NULL, HFILL }},
		{ &hf_v120_header_break8,
		  { "Break condition", "v120.header.break", FT_BOOLEAN, 8, TFS(&tfs_yes_no), 0x40,
		    NULL, HFILL }},
		{ &hf_v120_header_error_control8,
		  { "Error control C1/C2", "v120.error_control", FT_UINT8, BASE_HEX, NULL, 0x0C,
		    NULL, HFILL }},
		{ &hf_v120_header_segb8,
		  { "Bit B", "v120.header.segb", FT_BOOLEAN, 8, TFS(&tfs_segmentation_no_segmentation), 0x02,
		    NULL, HFILL }},
		{ &hf_v120_header_segf8,
		  { "Bit F", "v120.header.segf", FT_BOOLEAN, 8, TFS(&tfs_segmentation_no_segmentation), 0x01,
		    NULL, HFILL }},
		{ &hf_v120_header16,
		  { "Header", "v120.header", FT_UINT16, BASE_HEX, NULL, 0x0,
		    NULL, HFILL }},
		{ &hf_v120_header_ext16,
		  { "Extension octet", "v120.header.ext", FT_BOOLEAN, 16, TFS(&tfs_yes_no), 0x80,
		    NULL, HFILL }},
		{ &hf_v120_header_break16,
		  { "Break condition", "v120.header.break", FT_BOOLEAN, 16, TFS(&tfs_yes_no), 0x40,
		    NULL, HFILL }},
		{ &hf_v120_header_error_control16,
		  { "Error control C1/C2", "v120.error_control", FT_UINT16, BASE_HEX, NULL, 0x0C,
		    NULL, HFILL }},
		{ &hf_v120_header_segb16,
		  { "Bit B", "v120.header.segb", FT_BOOLEAN, 16, TFS(&tfs_segmentation_no_segmentation), 0x02,
		    NULL, HFILL }},
		{ &hf_v120_header_segf16,
		  { "Bit F", "v120.header.segf", FT_BOOLEAN, 16, TFS(&tfs_segmentation_no_segmentation), 0x01,
		    NULL, HFILL }},
		{ &hf_v120_header_e,
		  { "E", "v120.header.e", FT_BOOLEAN, 16, TFS(&tfs_yes_no), 0x8000,
		    NULL, HFILL }},
		{ &hf_v120_header_dr,
		  { "DR", "v120.header.dr", FT_BOOLEAN, 16, TFS(&tfs_yes_no), 0x4000,
		    NULL, HFILL }},
		{ &hf_v120_header_sr,
		  { "SR", "v120.header.sr", FT_BOOLEAN, 16, TFS(&tfs_yes_no), 0x2000,
		    NULL, HFILL }},
		{ &hf_v120_header_rr,
		  { "RR", "v120.header.rr", FT_BOOLEAN, 16, TFS(&tfs_yes_no), 0x1000,
		    NULL, HFILL }},
	};
	static gint *ett[] = {
		&ett_v120,
		&ett_v120_address,
		&ett_v120_control,
		&ett_v120_header,
	};

	proto_v120 = proto_register_protocol("Async data over ISDN (V.120)",
					     "V.120", "v120");
	proto_register_field_array (proto_v120, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));

	register_dissector("v120", dissect_v120, proto_v120);
}

/*
 * 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:
 */
