/* packet-pdc.c
 * Routines for PDC dissection
 * Copyright 2014, Antony Bridle <antony.bridle@nats.co.uk>
 *
 * 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 "packet-tcp.h"

void proto_register_pdc(void);
void proto_reg_handoff_pdc(void);

/*PDC Protocol*/
#define PDC_PROCOTOL "PDC"

/* PDC version */
#define PDC_VERSION 2

#define SIMPDU	1
#define RSMPDU	2
#define DRMPDU	3
#define DTMPDU	4
#define ADMPDU	5
#define EDMPDU	6
#define AKMPDU	8

/*Variable length Parameter Codes*/
#define PARAM_CODE_VERSION	2
#define PARAM_CODE_REFERENCES	3
#define PARAM_CODE_TRANSPORT	4

/* required for the TCP split packet combining */
#define PDC_MSG_SIZE_FIELD_LENGTH 2 /* minimum amount of data to find out how big the split packet should be when recombined */
#define FRAME_HEADER_LEN 8

/* global handle for our dissector */
static dissector_handle_t pdc_tcp_handle;

/* global handle for calling asterix decoder if required */
static dissector_handle_t asterix_handle;

static int		  proto_pdc;

/*HF Declarations*/
static int hf_pdc_len;
static int hf_pdc_mpdu_code;
static int hf_pdc_credit;
static int hf_pdc_simpdu_state;
static int hf_pdc_yr_admu_nr;
static int hf_pdc_akmpdu_mns;
static int hf_pdc_akmpdu_cdt;
static int hf_pdc_simpdu_var;
static int hf_pdc_simpdu_var_len;
static int hf_pdc_simpdu_param;
static int hf_pdc_simpdu_var_version;
static int hf_pdc_simpdu_var_REFSRC;
static int hf_pdc_simpdu_var_REFDEST;
static int hf_pdc_simpdu_var_TSEL;
static int hf_pdc_drmpdu_abort;
static int hf_pdc_drmpdu_reason;
static int hf_pdc_drmpdu_mode;
static int hf_pdc_drmpdu_init;
static int hf_pdc_dtmpdu_user_size;
static int hf_pdc_admpdu_admpdunr;
static int hf_pdc_admpdu_size;

/*Tree Declarations*/
static int ett_pdc;
static int ett_pdc_simpdu_var;


/*Value String Declarations*/
static const value_string valstr_simpdu_state[] = {
	{ 1, "Operational" },
	{ 2, "Standby" },
	{ 3, "Master" },
	{ 4, "Slave" },
	{ 5, "Single" },
	{ 0, NULL }
};

static const value_string valstr_simpdu_param[] = {
	{ 2, "Version Number" },
	{ 3, "References" },
	{ 4, "Transport Selector" },
	{ 0, NULL }
};

static const value_string valstr_mpdus[] = {
	{ 1, "State Information" },
	{ 2, "Request State" },
	{ 3, "Disconnect Request" },
	{ 4, "Data" },
	{ 5, "Acknowledged Data" },
	{ 6, "Expedited Data" },
	{ 8, "Data Acknowledgement" },
	{ 0, NULL }
};

static const value_string valstr_drmpdu_abort[] = {
	{ 0, "Orderly Release" },
	{ 1, "Abortive Release" },
	{ 0, NULL }
};

static const value_string valstr_drmpdu_mode[] = {
	{ 0, "Node Shutdown" },
	{ 7, "PDC Release"},
	{ 0, NULL }
};

static const value_string valstr_drmpdu_initatior[] = {
	{ 0, "Server" },
	{ 15, "Client"},
	{ 0, NULL }
};

static const value_string valstr_drmpdu_reason[] = {
	{ 0, "Reason Not Specified" },
	{ 1, "Normal Disconnect Initiated by the MS-User" },
	{ 2, "Protocol Error" },
	{ 3, "Connection Request Refused" },
	{ 4, "The Remote Operational MS Entity Does Not Respond" },
	{ 5, "The Protocol Version Is Not Supported" },
	{ 6, "Mismatched References" },
	{ 0, NULL }
};

/* start of functions here */
static int dissect_simpdu(tvbuff_t *tvb, proto_tree *tree, uint16_t offset, uint8_t lenIndicator)
{
	int	    bytesProcessed;
	uint8_t	    paramCode;
	proto_item *simpduItem;
	proto_tree *simpduVarTree;
	proto_tree *simpduVarTree1;

	bytesProcessed = 0;

	/*Add the Credit allocation*/
	proto_tree_add_item(tree, hf_pdc_credit, tvb, offset, 1, ENC_BIG_ENDIAN);
	bytesProcessed += 1;

	/*Add the State*/
	proto_tree_add_item(tree, hf_pdc_simpdu_state, tvb, offset + bytesProcessed , 1, ENC_BIG_ENDIAN);
	bytesProcessed += 1;

	/*Add the YR-ADMU-NR*/
	proto_tree_add_item(tree, hf_pdc_yr_admu_nr, tvb, offset + bytesProcessed , 4, ENC_BIG_ENDIAN);
	bytesProcessed += 4;

	/*Determine what's in the variable part*/
	if (lenIndicator > 7)
	{
		/*Add the Variable Length Tree*/
		simpduItem = proto_tree_add_item (tree, hf_pdc_simpdu_var, tvb, offset + bytesProcessed, lenIndicator - 7, ENC_NA);
		simpduVarTree = proto_item_add_subtree (simpduItem, ett_pdc_simpdu_var);

		while ((offset + bytesProcessed) < ( lenIndicator + 1 ))
		{
			/*Get the parameter code*/
			paramCode  = tvb_get_uint8(tvb, offset + bytesProcessed);
			simpduItem = proto_tree_add_item (simpduVarTree, hf_pdc_simpdu_param, tvb, offset + bytesProcessed,      1, ENC_BIG_ENDIAN);
			simpduVarTree1 = proto_item_add_subtree (simpduItem, ett_pdc_simpdu_var);
			bytesProcessed += 1;
			switch (paramCode)
			{
			case PARAM_CODE_VERSION:
				proto_tree_add_item(simpduVarTree1, hf_pdc_simpdu_var_len,     tvb, offset + bytesProcessed,     1, ENC_BIG_ENDIAN);
				proto_tree_add_item(simpduVarTree1, hf_pdc_simpdu_var_version, tvb, offset + bytesProcessed + 1, 1, ENC_BIG_ENDIAN);
				bytesProcessed += 2;
				break;
			case PARAM_CODE_REFERENCES:
				proto_tree_add_item(simpduVarTree1, hf_pdc_simpdu_var_len,     tvb, offset + bytesProcessed,     1, ENC_BIG_ENDIAN);
				proto_tree_add_item(simpduVarTree1, hf_pdc_simpdu_var_REFSRC,  tvb, offset + bytesProcessed + 1, 2, ENC_BIG_ENDIAN);
				proto_tree_add_item(simpduVarTree1, hf_pdc_simpdu_var_REFDEST, tvb, offset + bytesProcessed + 3, 2, ENC_BIG_ENDIAN);
				bytesProcessed += 5;
				break;
			case PARAM_CODE_TRANSPORT:
				proto_tree_add_item(simpduVarTree1, hf_pdc_simpdu_var_len,     tvb, offset + bytesProcessed,     1, ENC_BIG_ENDIAN);
				proto_tree_add_item(simpduVarTree1, hf_pdc_simpdu_var_TSEL,    tvb, offset + bytesProcessed + 1, 2, ENC_BIG_ENDIAN);
				bytesProcessed += 3;
				break;
			}
		} /* end of whileloop */
	}
	return (bytesProcessed);
}

static int dissect_rsmpdu(void)
{
	return 0;
}

static int dissect_drmpdu(tvbuff_t *tvb, proto_tree *tree, uint16_t offset)
{
	/*DR-MPDU*/
	proto_tree_add_item(tree, hf_pdc_drmpdu_abort,  tvb, offset,     1, ENC_BIG_ENDIAN);
	proto_tree_add_item(tree, hf_pdc_drmpdu_mode,   tvb, offset,     1, ENC_BIG_ENDIAN);
	proto_tree_add_item(tree, hf_pdc_drmpdu_init,   tvb, offset,     1, ENC_BIG_ENDIAN);
	proto_tree_add_item(tree, hf_pdc_drmpdu_reason, tvb, offset + 1, 1, ENC_BIG_ENDIAN);

	return 2;
}

#if (PDC_VERSION == 2)
static int dissect_admpdu(tvbuff_t *tvb, proto_tree *parent_tree, proto_tree *tree, uint16_t offset, packet_info *pinfo)
{
	uint16_t	  userDataLen;
	uint16_t	  returnLen;
	tvbuff_t *asterixTVB;

	/*Add the ad*/
	proto_tree_add_item(tree, hf_pdc_admpdu_admpdunr, tvb, offset, 4, ENC_BIG_ENDIAN);
	offset += 4;

	proto_tree_add_item(tree, hf_pdc_admpdu_size, tvb, offset, 2, ENC_BIG_ENDIAN);
	/* length of user data field */
	userDataLen = tvb_get_ntohs(tvb, offset);
	offset += 2;

	returnLen = userDataLen + 6;
	asterixTVB = tvb_new_subset_length(tvb, offset, userDataLen);

	if (asterix_handle != NULL)
		call_dissector(asterix_handle, asterixTVB, pinfo, parent_tree);

	return (returnLen);
}
#else
static int dissect_admpdu(tvbuff_t *tvb, proto_tree *parent_tree _U_, proto_tree *tree, uint16_t offset, packet_info *pinfo _U_)
{
	/*Add the ad*/
	proto_tree_add_item(tree, hf_pdc_admpdu_admpdunr, tvb, offset, 4, ENC_BIG_ENDIAN);

	return 2;
}
#endif

#if (PDC_VERSION == 2)
static int dissect_dtmpdu(tvbuff_t *tvb, proto_tree *parent_tree, proto_tree *tree, uint16_t offset, packet_info *pinfo)
{
	uint16_t	  userDataLen;
	uint16_t	  returnLen;
	tvbuff_t *asterixTVB;

	proto_tree_add_item(tree, hf_pdc_dtmpdu_user_size, tvb, offset, 2, ENC_BIG_ENDIAN);
	/* length of user data field */
	userDataLen = tvb_get_ntohs(tvb, 2);
	returnLen  = userDataLen + 2;
	asterixTVB = tvb_new_subset_length(tvb, offset + 2, userDataLen);

	if (asterix_handle != NULL)
		call_dissector(asterix_handle, asterixTVB, pinfo, parent_tree);

	return (returnLen);
}
#else
static int dissect_dtmpdu(tvbuff_t *tvb _U_, proto_tree *parent_tree _U_, proto_tree *tree _U_, uint16_t offset _U_, packet_info *pinfo _U_)
{
	return 2;
}
#endif


#if (PDC_VERSION == 2)
static int dissect_edmpdu(tvbuff_t *tvb, proto_tree *parent_tree, proto_tree *tree, uint16_t offset, packet_info *pinfo)
{
	uint16_t	  userDataLen;
	uint16_t	  returnLen;
	tvbuff_t *asterixTVB;

	proto_tree_add_item(tree, hf_pdc_dtmpdu_user_size, tvb, offset, 2, ENC_BIG_ENDIAN);
	/* length of user data field */
	userDataLen = tvb_get_ntohs(tvb, 2);
	returnLen   = userDataLen + 2;
	asterixTVB  = tvb_new_subset_length(tvb, offset + 2, userDataLen);

	if (asterix_handle != NULL)
		call_dissector(asterix_handle, asterixTVB, pinfo, parent_tree);

	return (returnLen);
}
#else
static int dissect_edmpdu(tvbuff_t *tvb _U_, proto_tree *parent_tree _U_, proto_tree *tree _U_, uint16_t offset _U_, packet_info *pinfo _U_)
{
	return 2;
}
#endif

static int dissect_akmpdu(tvbuff_t *tvb, proto_tree *tree, uint16_t offset)
{
	proto_tree_add_item(tree, hf_pdc_akmpdu_mns, tvb, offset,     2, ENC_BIG_ENDIAN);
	proto_tree_add_item(tree, hf_pdc_akmpdu_cdt, tvb, offset,     2, ENC_BIG_ENDIAN);
	proto_tree_add_item(tree, hf_pdc_yr_admu_nr, tvb, offset + 2, 4, ENC_BIG_ENDIAN);
	return (6);
}

static int dissect_pdc_packet(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo)
{
	unsigned	    i = 0;
	uint8_t	    len_indicator;
	uint8_t	    mpduCode;
	uint16_t	    length;
	proto_item *pdcPacketItem;
	proto_tree *pdcPacketTree;

	length = 0;

	/*Get the length indictor and the MPDU Code*/
	len_indicator  = tvb_get_uint8 (tvb, i);
	mpduCode       = tvb_get_uint8 (tvb, i + 1);
	length	      += 2;

	/*Add the PDC Tree*/
	pdcPacketItem = proto_tree_add_item (tree, proto_pdc, tvb, i, len_indicator + 1, ENC_NA);
	pdcPacketTree = proto_item_add_subtree (pdcPacketItem, ett_pdc);

	/*Add the Length and packet type*/
	proto_tree_add_item(pdcPacketTree, hf_pdc_len, tvb, i, 1, ENC_BIG_ENDIAN);
	proto_tree_add_item(pdcPacketTree, hf_pdc_mpdu_code, tvb, i + 1, 1, ENC_BIG_ENDIAN);

	/*Call the correct dissecting function*/
	switch (mpduCode)
	{
	case SIMPDU:
		length += dissect_simpdu(tvb, pdcPacketTree, length, len_indicator);
		col_set_str(pinfo->cinfo, COL_INFO, "SIMPDU");
		break;
	case RSMPDU:
		length += dissect_rsmpdu();
		col_set_str(pinfo->cinfo, COL_INFO, "RSMPDU");
		break;
	case DRMPDU:
		length += dissect_drmpdu(tvb, pdcPacketTree, length);
		col_set_str(pinfo->cinfo, COL_INFO, "DRMPDU");
		break;
	case DTMPDU:
		length += dissect_dtmpdu(tvb, tree, pdcPacketTree, length, pinfo);
		col_set_str(pinfo->cinfo, COL_INFO, "DTMPDU");
		break;
	case ADMPDU:
		length += dissect_admpdu(tvb, tree, pdcPacketTree, length, pinfo);
		col_set_str(pinfo->cinfo, COL_INFO, "ADMPDU");
		break;
	case EDMPDU:
		length += dissect_edmpdu(tvb, tree, pdcPacketTree, length, pinfo);
		col_set_str(pinfo->cinfo, COL_INFO, "EDMPDU");
		break;
	case AKMPDU:
		length += dissect_akmpdu(tvb, pdcPacketTree, length);
		col_set_str(pinfo->cinfo, COL_INFO, "AKMPDU");
		break;
	default:
		break;
	};
	return (length);  /* XXX: returned length ignored by caller: Remove keeping track of data processed ?         */
			  /*      col_set_str() could then be done separately with 'if (tree)' around the dissection */
}

/* Actual dissector bits and bytes done here */
static int dissect_pdc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
	/*Set the Column*/
	col_set_str(pinfo->cinfo, COL_PROTOCOL, PDC_PROCOTOL );
	col_clear(pinfo->cinfo, COL_INFO);

	dissect_pdc_packet(tvb, tree, pinfo);

	return tvb_reported_length(tvb);
}

/* function to provide TCP split packet combiner with size of packet */
static unsigned get_pdc_message_len(packet_info *pinfo _U_, tvbuff_t *tvb,
                                 int offset, void *data _U_)
{
	unsigned  size;
	unsigned  extra;
	uint8_t mpdu_type;

	mpdu_type = tvb_get_uint8(tvb, offset+1);
	switch (mpdu_type)
	{
	case SIMPDU:
		size  = tvb_get_uint8(tvb, offset);
		extra = 1;
		break;
	case RSMPDU:
		size  = tvb_get_uint8(tvb, offset);
		extra = 1;
		break;
	case DRMPDU:
		size  =	tvb_get_uint8(tvb, offset);
		extra = 1;
		break;
	case DTMPDU:
		size  = tvb_get_ntohs(tvb, offset+2);
		extra = 4;
		break;
	case ADMPDU:
		size  = tvb_get_ntohs(tvb, offset+6);
		extra = 8;
		break;
	case EDMPDU:
		size  = tvb_get_uint8(tvb, offset);
		extra = 1;
		break;
	case AKMPDU:
		size  = tvb_get_uint8(tvb, offset)+1;
		extra = 0;
		break;
	default:
		size  = 0;
		extra = 0;
	}
	return size + extra;
}

/* top level call to recombine split tcp packets */

static int tcp_dissect_pdc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
	uint8_t mpdu_type;
	uint8_t minimum_bytes;

	mpdu_type = tvb_get_uint8(tvb,1);
	switch (mpdu_type)
	{
	case SIMPDU:
		minimum_bytes = 2;
		break;
	case RSMPDU:
		minimum_bytes = 2;
		break;
	case DRMPDU:
		minimum_bytes = 2;
		break;
	case DTMPDU:
		minimum_bytes = 4;
		break;
	case ADMPDU:
		minimum_bytes = 8;
		break;
	case EDMPDU:
		minimum_bytes = 2;
		break;
	case AKMPDU:
		minimum_bytes = 2;
		break;
	default:
		minimum_bytes = 2;
		break;
	}
	tcp_dissect_pdus(tvb, pinfo, tree, true, minimum_bytes, get_pdc_message_len, dissect_pdc, NULL);
	return tvb_captured_length(tvb);
}

void proto_register_pdc(void)
{
	static hf_register_info hf[] =
	{
		{ &hf_pdc_len,
		  { "Length Indicator", "pdc.li",
		    FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

		{ &hf_pdc_mpdu_code,
		  { "MPDU code", "pdc.mpducode",
		    FT_UINT8, BASE_DEC, VALS(valstr_mpdus), 0x0, NULL, HFILL }},

		{ &hf_pdc_credit,
		  { "Credit", "pdc.cdt",
		    FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

		{ &hf_pdc_yr_admu_nr,
		  { "YR-ADMU-NR", "pdc.yradmunr",
		    FT_UINT32, BASE_DEC, NULL, 0x0, NULL , HFILL }},

		{ &hf_pdc_simpdu_state,
		  { "State", "pdc.state",
		    FT_UINT8, BASE_DEC, VALS(valstr_simpdu_state), 0x0, NULL, HFILL }},

		{ &hf_pdc_akmpdu_mns,
		  { "MNS", "pdc.akmpdu.mns",
		    FT_UINT16, BASE_DEC, NULL, 0x8000, NULL, HFILL }},

		{ &hf_pdc_akmpdu_cdt,
		  { "CDT", "pdc.akmpdu.cdt",
		    FT_UINT16, BASE_DEC, NULL, 0x07FF, NULL, HFILL }},

		{ &hf_pdc_simpdu_var,
		  { "Variable Part", "pdc.simpdu.variable",
		    FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }},

		{ &hf_pdc_simpdu_param,
		  { "Parameter", "pdc.simpdu.param",
		    FT_UINT8, BASE_DEC, VALS(valstr_simpdu_param), 0x0, NULL, HFILL }},

		{ &hf_pdc_simpdu_var_len,
		  { "Length", "pdc.simpdu.variable.length",
		    FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

		{ &hf_pdc_simpdu_var_version,
		  { "PDC Version Number", "pdc.simpdu.variable.version",
		    FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

		{ &hf_pdc_simpdu_var_REFSRC,
		  { "Reference Source", "pdc.simpdu.variable.refsrc",
		    FT_UINT32, BASE_DEC, NULL, 0x0,NULL, HFILL }},

		{ &hf_pdc_simpdu_var_REFDEST,
		  { "Reference Destination", "pdc.simpdu.variable.refdst",
		    FT_UINT32, BASE_DEC, NULL, 0x0,NULL, HFILL }},

		{ &hf_pdc_simpdu_var_TSEL,
		  { "Transport Selector", "pdc.simpdu.tsel",
		    FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},

		{ &hf_pdc_drmpdu_abort,
		  { "Abort", "pdc.drmpdu.abort",
		    FT_UINT8, BASE_DEC, VALS(valstr_drmpdu_abort), 0x80, NULL, HFILL }},

		{ &hf_pdc_drmpdu_reason,
		  { "Reason", "pdc.drmpdu.reason",
		    FT_UINT8, BASE_DEC, VALS(valstr_drmpdu_reason), 0x0, NULL, HFILL }},

		{ &hf_pdc_drmpdu_mode,
		  { "Mode", "pdc.drmpdu.mode",
		    FT_UINT8, BASE_DEC, VALS(valstr_drmpdu_mode), 0x70, NULL, HFILL }},

		{ &hf_pdc_drmpdu_init,
		  { "Reason", "pdc.drmpdu.init",
		    FT_UINT8, BASE_DEC, VALS(valstr_drmpdu_initatior), 0x0F, NULL, HFILL }},

		{ &hf_pdc_dtmpdu_user_size,
		  { "User Data Length", "pdc.dtmpdu.usersize",
		    FT_UINT16, BASE_DEC, NULL, 0x0, NULL , HFILL }},

		{ &hf_pdc_admpdu_admpdunr,
		  { "AD-MPDU-NR", "pdc.admpdu.admpdunr",
		    FT_UINT32,  BASE_DEC, NULL, 0x0, NULL , HFILL }},

		{ &hf_pdc_admpdu_size,
		  { "User Data Size", "pdc.admpdu.usersize",
		    FT_UINT16, BASE_DEC, NULL, 0x0, NULL , HFILL }},
	};

	/* Setup protocol subtree array */
	static int *ett[] = {
		&ett_pdc,
		&ett_pdc_simpdu_var
	};

	proto_pdc = proto_register_protocol (
		"PDC Protocol",	/* name       */
		"PDC",		/* short name */
		"pdc"		/* abbrev     */
		);

	/*Required Function Calls to register the header fields and subtrees used*/
	proto_register_field_array(proto_pdc, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));

	/* Register our dissector handle */
	pdc_tcp_handle = register_dissector("pdc", tcp_dissect_pdc, proto_pdc);
}

/* Function to add pdc dissector to tcp.port dissector table and to get handle for asterix dissector */
void proto_reg_handoff_pdc(void)
{
	asterix_handle = find_dissector_add_dependency("asterix", proto_pdc);
	dissector_add_for_decode_as_with_preference("tcp.port", pdc_tcp_handle);
}

/*
 * 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:
 */
