text: /* packet-pw-satop.c
   * Routines for CESoPSN PW dissection as per RFC5086.
   * Copyright 2009, Dmitry Trebich, Artem Tamazov <artem.tamazov@tellabs.com>
   *
   * Wireshark - Network traffic analyzer
   * By Gerald Combs <gerald@wireshark.org>
   * Copyright 1998 Gerald Combs
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version 2
   * of the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * History:
   * ---------------------------------
   * 16.03.2009 initial implementation for MPLS
   * 14.08.2009 added: support for IP/UDP demultiplexing
   * Not supported yet:
   * - All PW modes, except Basic NxDS0 mode.
   * - <Optional> RTP Headers (RFC3550)
   * - Decoding of PW payload
   */
  
  #include "config.h"
  
  #include <epan/packet.h>
  #include <epan/expert.h>
  
  #include "packet-mpls.h"
  #include "packet-pw-common.h"
  
  void proto_register_pw_cesopsn(void);
  void proto_reg_handoff_pw_cesopsn(void);
  
  static gint proto = -1;
  static gint ett = -1;
  
  static int hf_cw = -1;
  static int hf_cw_bits03 = -1;
  static int hf_cw_lm = -1;
  static int hf_cw_r = -1;
  static int hf_cw_frg = -1;
  static int hf_cw_len = -1;
  static int hf_cw_seq = -1;
  static int hf_payload = -1;
  static int hf_payload_l = -1;
  
  static expert_field ei_payload_size_invalid_undecoded = EI_INIT;
  static expert_field ei_cw_frg = EI_INIT;
  static expert_field ei_payload_size_invalid_error = EI_INIT;
  static expert_field ei_cw_bits03 = EI_INIT;
  static expert_field ei_pref_cw_len = EI_INIT;
  static expert_field ei_cw_lm = EI_INIT;
  static expert_field ei_packet_size_too_small = EI_INIT;
  
  static dissector_handle_t data_handle;
  static dissector_handle_t pw_padding_handle;
  
  const char pwc_longname_pw_cesopsn[] = "CESoPSN basic NxDS0 mode (no RTP support)";
  static const char shortname[] = "CESoPSN basic (no RTP)";
  
  static const value_string vals_cw_lm[] = {
  	/* note that bitmask in hs_register_info is 0xb == 1011B */
  	/* this is why 0x8 comes just after 0x3 */
  	{ 0x0,	"Normal situation - no AC faults" },
  	/*{ 0x1,	"Reserved combination" },*/
  	{ 0x2,	"AC Fault - RDI condition" },
  	{ 0x3,	"Reserved for CESoPSN signaling" },
  	{ 0x8,	"AC Fault - TDM data is invalid" },
  	/*{ 0x9,	"Reserved combination" },*/
  	/*{ 0xa,	"Reserved combination" },*/
  	/*{ 0xb,	"Reserved combination" },*/
  	{ 0,	NULL }
  };
  
  
  static
  void dissect_pw_cesopsn( tvbuff_t * tvb_original
  						,packet_info * pinfo
  						,proto_tree * tree
  						,pwc_demux_type_t demux)
  {
  	const int encaps_size = 4; /*RTP header in encapsulation is not supported yet*/
  	gint      packet_size;
  	gint      payload_size;
  	gint      padding_size;
  	int properties;
  
  	packet_size = tvb_reported_length_remaining(tvb_original, 0);
  
  	/*
  	 * FIXME
  	 * "4" below should be replaced by something like "min_packet_size_this_dissector"
  	 * Also call to dissect_try_cw_first_nibble() should be moved before this block
  	 */
  	if (packet_size < 4) /* 4 is smallest size which may be sensible (for PWACH dissector) */
  	{
  		proto_item  *item;
  		item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
  		expert_add_info_format(pinfo, item, &ei_packet_size_too_small,
  				       "PW packet size (%d) is too small to carry sensible information"
  				       ,(int)packet_size);
  		col_set_str(pinfo->cinfo, COL_PROTOCOL, shortname);
  		col_set_str(pinfo->cinfo, COL_INFO, "Malformed: PW packet is too small");
  		return;
  	}
  
  	switch (demux)
  	{
  	case PWC_DEMUX_MPLS:
  		if (dissect_try_cw_first_nibble(tvb_original, pinfo, tree))
  		{
  			return;
  		}
  		break;
  	case PWC_DEMUX_UDP:
  		break;
  	default:
  		DISSECTOR_ASSERT_NOT_REACHED();
  		return;
  	}
  
  	/* check how "good" is this packet */
  	/* also decide payload length from packet size and CW */
  	properties = PWC_PACKET_PROPERTIES_T_INITIALIZER;
  	if (0 != (tvb_get_guint8(tvb_original, 0) & 0xf0 /*bits03*/))
  	{
  		properties |= PWC_CW_BAD_BITS03;
  	}
  	if (0 != (tvb_get_guint8(tvb_original, 1) & 0xc0 /*frag*/))
  	{
  		properties |= PWC_CW_BAD_FRAG;
  	}
  	{
  		/* RFC5086:
  		 * [LEN (bits (10 to 15) MAY be used to carry the length of the CESoPSN
  		 * packet (defined as the size of the CESoPSN header + the payload size)
  		 * if it is less than 64 bytes, and MUST be set to zero otherwise.
  		 * Note:  If fixed RTP header is used in the encapsulation, it is
  		 * considered part of the CESoPSN header.]
  		 *
  		 * Note that this differs from RFC4385's definition of length:
  		 * [ If the MPLS payload is less than 64 bytes, the length field
  		 * MUST be set to the length of the PW payload...]
  		 *
  		 * We will use RFC5086's definition here.
  		 */
  		int  cw_len;
  		gint payload_size_from_packet;
  
  		cw_len = tvb_get_guint8(tvb_original, 1) & 0x3f;
  		payload_size_from_packet = packet_size - encaps_size;
  		if (cw_len != 0)
  		{
  			gint payload_size_from_cw;
  			payload_size_from_cw = cw_len - encaps_size;
  			/*
  			 * Assumptions for error case,
  			 * will be overwritten if no errors found:
  			 */
  			payload_size = payload_size_from_packet;
  			padding_size = 0;
  
  			if (payload_size_from_cw < 0)
  			{
  				properties |= PWC_CW_BAD_PAYLEN_LT_0;
  			}
  			else if (payload_size_from_cw > payload_size_from_packet)
  			{
  				properties |= PWC_CW_BAD_PAYLEN_GT_PACKET;
  			}
  			else if (payload_size_from_packet >= 64)
  			{
  				properties |= PWC_CW_BAD_LEN_MUST_BE_0;
  			}
  			else /* ok */
  			{
  				payload_size = payload_size_from_cw;
  				padding_size = payload_size_from_packet - payload_size_from_cw; /* >=0 */
  			}
  		}
  		else
  		{
  			payload_size = payload_size_from_packet;
  			padding_size = 0;
  		}
  	}
  
  	{
  		guint8 cw_lm;
  		cw_lm = tvb_get_guint8(tvb_original, 0) & 0x0b /*l+mod*/;
  		if (NULL == try_val_to_str(cw_lm, vals_cw_lm))
  		{
  			properties |= PWC_CW_SUSPECT_LM;
  		}
  
  		{
  			guint8 l_bit, m_bits;
  			l_bit  = (cw_lm & 0x08) >> 3;
  			m_bits = (cw_lm & 0x03) >> 0;
  			if ((l_bit == 0 && m_bits == 0x0) /*CESoPSN data packet - normal situation*/
  			    ||(l_bit == 0 && m_bits == 0x2) /*CESoPSN data packet - RDI on the AC*/ )
  			{
  				if ((payload_size == 0) || ((payload_size % 8) != 0))
  				{
  					properties |= PWC_PAY_SIZE_BAD;
  				}
  			}
  			else if (l_bit == 1 && m_bits == 0x0) /*TDM data is invalid; payload MAY be omitted*/
  			{
  				/*allow any size of payload*/
  			}
  			else /*reserved combinations*/
  			{
  				/*allow any size of payload*/
  			}
  		}
  	}
  
  	/* fill up columns*/
  	col_set_str(pinfo->cinfo, COL_PROTOCOL, shortname);
  	col_clear(pinfo->cinfo, COL_INFO);
  	if (properties & PWC_ANYOF_CW_BAD)
  	{
  		col_set_str(pinfo->cinfo, COL_INFO, "CW:Bad, ");
  	}
  	else if (properties & PWC_ANYOF_CW_SUSPECT)
  	{
  		col_append_str(pinfo->cinfo, COL_INFO, "CW:Suspect, ");
  	}
  
  	if (properties & PWC_PAY_SIZE_BAD)
  	{
  		col_append_str(pinfo->cinfo, COL_INFO, "Payload size:Bad, ");
  	}
  
  	col_append_fstr(pinfo->cinfo, COL_INFO, "TDM octets:%d", (int)payload_size);
  
  	if (padding_size != 0)
  	{
  		col_append_fstr(pinfo->cinfo, COL_INFO, ", Padding:%d", (int)padding_size);
  	}
  
  	{
  		proto_item* item;
  		item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
  		pwc_item_append_cw(item,tvb_get_ntohl(tvb_original, 0),TRUE);
  		pwc_item_append_text_n_items(item,(int)payload_size,"octet");
  		{
  			proto_tree* tree2;
  			tree2 = proto_item_add_subtree(item, ett);
  			{
  				tvbuff_t* tvb;
  				proto_item* item2;
  				tvb = tvb_new_subset_length(tvb_original, 0, PWC_SIZEOF_CW);
  				item2 = proto_tree_add_item(tree2, hf_cw, tvb, 0, -1, ENC_NA);
  				pwc_item_append_cw(item2,tvb_get_ntohl(tvb, 0),FALSE);
  				{
  					proto_tree* tree3;
  					tree3 = proto_item_add_subtree(item, ett);
  					{
  						proto_item* item3;
  						if (properties & PWC_CW_BAD_BITS03) /*display only if value is wrong*/
  						{
  							item3 = proto_tree_add_item(tree3, hf_cw_bits03, tvb, 0, 1, ENC_BIG_ENDIAN);
  							expert_add_info(pinfo, item3, &ei_cw_bits03);
  						}
  
  						item3 = proto_tree_add_item(tree3, hf_cw_lm,  tvb, 0, 1, ENC_BIG_ENDIAN);
  						if (properties & PWC_CW_SUSPECT_LM)
  						{
  							expert_add_info(pinfo, item3, &ei_cw_lm);
  						}
  
  						proto_tree_add_item(tree3, hf_cw_r, tvb, 0, 1, ENC_BIG_ENDIAN);
  
  						item3 = proto_tree_add_item(tree3, hf_cw_frg, tvb, 1, 1, ENC_BIG_ENDIAN);
  						if (properties & PWC_CW_BAD_FRAG)
  						{
  							expert_add_info(pinfo, item3, &ei_cw_frg);
  						}
  
  						item3 = proto_tree_add_item(tree3, hf_cw_len, tvb, 1, 1, ENC_BIG_ENDIAN);
  						if (properties & PWC_CW_BAD_PAYLEN_LT_0)
  						{
  							expert_add_info_format(pinfo, item3, &ei_pref_cw_len,
  								"Bad Length: too small, must be > %d",
  								(int)encaps_size);
  						}
  						if (properties & PWC_CW_BAD_PAYLEN_GT_PACKET)
  						{
  							expert_add_info_format(pinfo, item3, &ei_pref_cw_len,
  								"Bad Length: must be <= than PSN packet size (%d)",
  								(int)packet_size);
  						}
  						if (properties & PWC_CW_BAD_LEN_MUST_BE_0)
  						{
  							expert_add_info_format(pinfo, item3, &ei_pref_cw_len,
  								"Bad Length: must be 0 if CESoPSN packet size (%d) is > 64",
  								(int)packet_size);
  						}
  
  						proto_tree_add_item(tree3, hf_cw_seq, tvb, 2, 2, ENC_BIG_ENDIAN);
  
  					}
  				}
  			}
  		}
  
  		/* payload */
  		if (payload_size == 0)
  		{
  			if (properties & PWC_PAY_SIZE_BAD)
  			{
  				expert_add_info_format(pinfo, item, &ei_payload_size_invalid_error,
  					"CESoPSN payload: none found. Size of payload must be <> 0");
  			}
  			else
  			{
  				expert_add_info_format(pinfo, item, &ei_payload_size_invalid_undecoded,
  					"CESoPSN payload: omitted to conserve bandwidth");
  			}
  		}
  		else
  		{
  			proto_tree* tree2;
  			tree2 = proto_item_add_subtree(item, ett);
  			{
  				proto_item* item2;
  				tvbuff_t* tvb;
  				tvb = tvb_new_subset_length(tvb_original, PWC_SIZEOF_CW, payload_size);
  				item2 = proto_tree_add_item(tree2, hf_payload, tvb, 0, -1, ENC_NA);
  				pwc_item_append_text_n_items(item2,(int)payload_size,"octet");
  				if (properties & PWC_PAY_SIZE_BAD)
  				{
  					expert_add_info_format(pinfo, item2, &ei_payload_size_invalid_error,
  						"CESoPSN packet payload size must be multiple of 8");
  				}
  				tree2 = proto_item_add_subtree(item2, ett);
  				call_dissector(data_handle, tvb, pinfo, tree2);
  				item2 = proto_tree_add_int(tree2, hf_payload_l, tvb, 0, 0
  					,(int)payload_size); /* allow filtering */
  				PROTO_ITEM_SET_HIDDEN(item2);
  			}
  		}
  
  		/* padding */
  		if (padding_size > 0)
  		{
  			proto_tree* tree2;
  			tree2 = proto_item_add_subtree(item, ett);
  			{
  				tvbuff_t* tvb;
  				tvb = tvb_new_subset(tvb_original, PWC_SIZEOF_CW + payload_size, padding_size, -1);
  				call_dissector(pw_padding_handle, tvb, pinfo, tree2);
  			}
  		}
  	}
  	return;
  }
  
  
  static
  void dissect_pw_cesopsn_mpls( tvbuff_t * tvb_original, packet_info * pinfo, proto_tree * tree)
  {
  	dissect_pw_cesopsn(tvb_original,pinfo,tree,PWC_DEMUX_MPLS);
  	return;
  }
  
  
  static
  void dissect_pw_cesopsn_udp( tvbuff_t * tvb_original, packet_info * pinfo, proto_tree * tree)
  {
  	dissect_pw_cesopsn(tvb_original,pinfo,tree,PWC_DEMUX_UDP);
  	return;
  }
  
  
  void proto_register_pw_cesopsn(void)
  {
  	static hf_register_info hf[] = {
  		{ &hf_cw	,{"Control Word"		,"pwcesopsn.cw"
  				  ,FT_NONE			,BASE_NONE		,NULL
  				  ,0				,NULL			,HFILL }},
  
  		{&hf_cw_bits03,{"Bits 0 to 3"			,"pwcesopsn.cw.bits03"
  				,FT_UINT8			,BASE_DEC		,NULL
  				,0xf0				,NULL			,HFILL }},
  
  		{ &hf_cw_lm, 	{"L+M bits"			,"pwcesopsn.cw.lm"
  				 ,FT_UINT8			,BASE_HEX		,VALS(vals_cw_lm)
  				 ,0x0b	  			,NULL 			,HFILL }},
  
  		{&hf_cw_r,	{"R bit: Local CE-bound IWF"	,"pwcesopsn.cw.rbit"
  				 ,FT_UINT8			,BASE_DEC		,VALS(pwc_vals_cw_r_bit)
  				 ,0x04				,NULL			,HFILL }},
  
  		{&hf_cw_frg,	{"Fragmentation"		,"pwcesopsn.cw.frag"
  				 ,FT_UINT8			,BASE_DEC		,VALS(pwc_vals_cw_frag)
  				 ,0xc0				,NULL			,HFILL }},
  
  		{&hf_cw_len,	{"Length"			,"pwcesopsn.cw.length"
  				 ,FT_UINT8			,BASE_DEC		,NULL
  				 ,0x3f				,NULL			,HFILL }},
  
  		{&hf_cw_seq,	{"Sequence number"		,"pwcesopsn.cw.seqno"
  				 ,FT_UINT16			,BASE_DEC		,NULL
  				 ,0				,NULL			,HFILL }},
  
  		{&hf_payload	,{"TDM payload"			,"pwcesopsn.payload"
  				  ,FT_BYTES			,BASE_NONE		,NULL
  				  ,0				,NULL			,HFILL }},
  
  		{&hf_payload_l	,{"TDM payload length"		,"pwcesopsn.payload.len"
  				  ,FT_INT32			,BASE_DEC		,NULL
  				  ,0				,NULL			,HFILL }}
  	};
  
  	static gint *ett_array[] = {
  		&ett
  	};
  	static ei_register_info ei[] = {
  		{ &ei_packet_size_too_small, { "pwcesopsn.packet_size_too_small", PI_MALFORMED, PI_ERROR, "PW packet size is too small to carry sensible information", EXPFILL }},
  		{ &ei_cw_bits03, { "pwcesopsn.cw.bits03.not_zero", PI_MALFORMED, PI_ERROR, "Bits 0..3 of Control Word must be 0", EXPFILL }},
  		{ &ei_cw_lm, { "pwcesopsn.cw.lm.reserved", PI_UNDECODED, PI_WARN, "Reserved combination of L and Modifier bits", EXPFILL }},
  		{ &ei_cw_frg, { "pwcesopsn.cw.frag.not_allowed", PI_MALFORMED, PI_ERROR, "Fragmentation of payload is not allowed for basic CESoPSN mode", EXPFILL }},
  		{ &ei_pref_cw_len, { "pwcesopsn.cw.length.invalid", PI_MALFORMED, PI_ERROR, "Bad Length: too small", EXPFILL }},
  		{ &ei_payload_size_invalid_error, { "pwcesopsn.payload.size_invalid", PI_MALFORMED, PI_ERROR, "CESoPSN payload size invalid", EXPFILL }},
  		{ &ei_payload_size_invalid_undecoded, { "pwcesopsn.payload.undecoded", PI_UNDECODED, PI_NOTE, "CESoPSN payload: omitted to conserve bandwidth", EXPFILL }},
  	};
  	expert_module_t* expert_pwcesopsn;
  
  	proto = proto_register_protocol(pwc_longname_pw_cesopsn, shortname, "pwcesopsn");
  	proto_register_field_array(proto, hf, array_length(hf));
  	proto_register_subtree_array(ett_array, array_length(ett_array));
  	expert_pwcesopsn = expert_register_protocol(proto);
  	expert_register_field_array(expert_pwcesopsn, ei, array_length(ei));
  	register_dissector("pw_cesopsn_udp", dissect_pw_cesopsn_udp, proto);
  	return;
  }
  
  
  void proto_reg_handoff_pw_cesopsn(void)
  {
  	dissector_handle_t pw_cesopsn_mpls_handle;
  
  	data_handle = find_dissector("data");
  	pw_padding_handle = find_dissector("pw_padding");
  
  	/* For Decode As */
  	pw_cesopsn_mpls_handle = create_dissector_handle( dissect_pw_cesopsn_mpls, proto );
  	dissector_add_for_decode_as("mpls.label", pw_cesopsn_mpls_handle);
  
  	dissector_add_for_decode_as("udp.port", find_dissector("pw_cesopsn_udp"));
  	return;
  }
  
  /*
   * Editor modelines  -  http://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:
   */
  