/* packet-rtcdc.c
 * Routines for the RTCWeb Data Channel Protocol dissection
 * as specified in 
 * http://tools.ietf.org/html/draft-jesup-rtcweb-data-protocol-03
 *
 * Copyright 2012, Michael Tuexen <tuexen@wireshark.org>
 *
 * $Id$
 *
 * 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.
 */

#include "config.h"

#include <glib.h>

#include <epan/expert.h>
#include <epan/packet.h>
#include <epan/prefs.h>

void proto_reg_handoff_rtcdc(void);

/* PPID used for this protocol */
static guint32 rtcdc_ppid = 50;

/* Initialize the protocol and registered fields */
static int proto_rtcdc = -1;
static int hf_message_type = -1;
static int hf_channel_type = -1;
static int hf_flags = -1;
static int hf_flags_reserved = -1;
static int hf_unordered_allowed = -1;
static int hf_reliability = -1;
static int hf_priority = -1;
static int hf_label = -1;
static int hf_error = -1;
static int hf_sid = -1;

/* Initialize the subtree pointers */
static gint ett_rtcdc = -1;
static gint ett_flags = -1;

#define DATA_CHANNEL_OPEN_REQUEST   0x00
#define DATA_CHANNEL_OPEN_RESPONSE  0x01
#define DATA_CHANNEL_ACK            0x02

static const value_string message_type_values[] = {
	{ DATA_CHANNEL_OPEN_REQUEST,  "DATA_CHANNEL_OPEN_REQUEST"  },
	{ DATA_CHANNEL_OPEN_RESPONSE, "DATA_CHANNEL_OPEN_RESPONSE" },
	{ DATA_CHANNEL_ACK,           "DATA_CHANNEL_ACK"           },
	{ 0,                          NULL                         }
};

#define DATA_CHANNEL_RELIABLE                0x00
#define DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT 0x01
#define DATA_CHANNEL_PARTIAL_RELIABLE_TIMED  0x02

static const value_string channel_type_values[] = {
	{ DATA_CHANNEL_RELIABLE,                "DATA_CHANNEL_RELIABLE"                },
	{ DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT, "DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT" },
	{ DATA_CHANNEL_PARTIAL_RELIABLE_TIMED,  "DATA_CHANNEL_PARTIAL_RELIABLE_TIMED"  },
	{ 0,                                    NULL                                   }
};

#define MESSAGE_TYPE_LENGTH 1
#define CHANNEL_TYPE_LENGTH 1
#define FLAGS_LENGTH        2
#define RELIABILITY_LENGTH  2
#define PRIORITY_LENGTH     2

#define MESSAGE_TYPE_OFFSET 0
#define CHANNEL_TYPE_OFFSET (MESSAGE_TYPE_OFFSET + MESSAGE_TYPE_LENGTH)
#define FLAGS_OFFSET        (CHANNEL_TYPE_OFFSET + CHANNEL_TYPE_LENGTH)
#define RELIABILITY_OFFSET  (FLAGS_OFFSET + FLAGS_LENGTH)
#define PRIORITY_OFFSET     (RELIABILITY_OFFSET + RELIABILITY_LENGTH)
#define LABEL_OFFSET        (PRIORITY_OFFSET + PRIORITY_LENGTH)

#define DATA_CHANNEL_FLAG_OUT_OF_ORDER_ALLOWED_MASK 0x0001
#define DATA_CHANNEL_FLAG_RESERVED_MASK             0xFFFE

static void
dissect_open_request_message(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *rtcdc_tree, proto_item *rtcdc_item _U_) {
	if (rtcdc_tree) {
		proto_tree *flags_tree;
		proto_item *flags_item;

		proto_tree_add_item(rtcdc_tree, hf_channel_type, tvb, CHANNEL_TYPE_OFFSET, CHANNEL_TYPE_LENGTH, ENC_BIG_ENDIAN);
		flags_item = proto_tree_add_item(rtcdc_tree, hf_flags, tvb, FLAGS_OFFSET, FLAGS_LENGTH, ENC_BIG_ENDIAN);
		flags_tree = proto_item_add_subtree(flags_item, ett_flags);
		proto_tree_add_item(flags_tree, hf_flags_reserved, tvb, FLAGS_OFFSET, FLAGS_LENGTH, ENC_BIG_ENDIAN);
		proto_tree_add_item(flags_tree, hf_unordered_allowed, tvb, FLAGS_OFFSET, FLAGS_LENGTH, ENC_BIG_ENDIAN);
		proto_tree_add_item(rtcdc_tree, hf_reliability, tvb, RELIABILITY_OFFSET, RELIABILITY_LENGTH, ENC_BIG_ENDIAN);
		proto_tree_add_item(rtcdc_tree, hf_priority, tvb, PRIORITY_OFFSET, PRIORITY_LENGTH, ENC_BIG_ENDIAN);
		proto_tree_add_item(rtcdc_tree, hf_label, tvb, LABEL_OFFSET, -1, ENC_BIG_ENDIAN);
	}
	return;
}

#define ERROR_LENGTH                 1
#define SID_LENGTH                   2
#define DATA_CHANNEL_RESPONSE_LENGTH (MESSAGE_TYPE_LENGTH + ERROR_LENGTH + FLAGS_LENGTH + SID_LENGTH)

#define ERROR_OFFSET                 (MESSAGE_TYPE_OFFSET + MESSAGE_TYPE_LENGTH)
#define SID_OFFSET                   (FLAGS_OFFSET + FLAGS_LENGTH)

static void
dissect_open_response_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *rtcdc_tree, proto_item *rtcdc_item) {
	if (tvb_length(tvb) > DATA_CHANNEL_RESPONSE_LENGTH) {
		expert_add_info_format(pinfo, rtcdc_item, PI_MALFORMED, PI_ERROR, "Message too long");
	}
	if (rtcdc_tree) {
		proto_tree_add_item(rtcdc_tree, hf_error, tvb, ERROR_OFFSET, ERROR_LENGTH, ENC_BIG_ENDIAN);
		proto_tree_add_item(rtcdc_tree, hf_flags, tvb, FLAGS_OFFSET, FLAGS_LENGTH, ENC_BIG_ENDIAN);
		proto_tree_add_item(rtcdc_tree, hf_sid, tvb, SID_OFFSET, SID_LENGTH, ENC_BIG_ENDIAN);
	}
	return;
}

#define DATA_CHANNEL_ACK_LENGTH MESSAGE_TYPE_LENGTH

static void
dissect_open_ack_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *rtcdc_tree _U_, proto_item *rtcdc_item) {
	if (tvb_length(tvb) > DATA_CHANNEL_ACK_LENGTH) {
		expert_add_info_format(pinfo, rtcdc_item, PI_MALFORMED, PI_ERROR, "Message too long");
	}
	return;
}

static int
dissect_rtcdc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
	proto_item *rtcdc_item;
	proto_tree *rtcdc_tree;
	guint8 message_type;

	message_type  = tvb_get_guint8(tvb, MESSAGE_TYPE_OFFSET);

	col_set_str(pinfo->cinfo, COL_PROTOCOL, "RTCDC");
	col_add_fstr(pinfo->cinfo, COL_INFO, "%s ", val_to_str_const(message_type, message_type_values, "reserved"));
	if (tree) {
		rtcdc_item = proto_tree_add_item(tree, proto_rtcdc, tvb, 0, -1, ENC_NA);
		rtcdc_tree = proto_item_add_subtree(rtcdc_item, ett_rtcdc);
		proto_tree_add_item(rtcdc_tree, hf_message_type, tvb, MESSAGE_TYPE_OFFSET, MESSAGE_TYPE_LENGTH, ENC_BIG_ENDIAN);
	} else {
		rtcdc_item = NULL;
		rtcdc_tree = NULL;
	}
	switch (message_type) {
	case DATA_CHANNEL_OPEN_REQUEST:
		dissect_open_request_message(tvb, pinfo, rtcdc_tree, rtcdc_item);
		break;
	case DATA_CHANNEL_OPEN_RESPONSE:
		dissect_open_response_message(tvb, pinfo, rtcdc_tree, rtcdc_item);
		break;
	case DATA_CHANNEL_ACK:
		dissect_open_ack_message(tvb, pinfo, rtcdc_tree, rtcdc_item);
		break;
	default:
		expert_add_info_format(pinfo, rtcdc_item, PI_MALFORMED, PI_ERROR, "Unknown message type");
		break;
	}
	return tvb_length(tvb);
}

void
proto_register_rtcdc(void)
{
	module_t *rtcdc_module;
	static hf_register_info hf[] = {
		{ &hf_message_type,      { "Message type",              "rtcdc.message_type",            FT_UINT8,   BASE_DEC,  VALS(message_type_values), 0x0,                                         NULL, HFILL } },
		{ &hf_channel_type,      { "Channel type",              "rtcdc.channel_type",            FT_UINT8,   BASE_DEC,  VALS(channel_type_values), 0x0,                                         NULL, HFILL } },
		{ &hf_flags,             { "Flags",                     "rtcdc.flags",                   FT_UINT16,  BASE_HEX,  NULL,                      0x0,                                         NULL, HFILL } },
		{ &hf_flags_reserved,    { "Reserved",                  "rtcdc.flags_reserved",          FT_UINT16,  BASE_HEX,  NULL,                      DATA_CHANNEL_FLAG_RESERVED_MASK,             NULL, HFILL } },
		{ &hf_unordered_allowed, { "Unordered allowed",         "rtcdc.flags_unordered_allowed", FT_BOOLEAN, 16,        NULL,                      DATA_CHANNEL_FLAG_OUT_OF_ORDER_ALLOWED_MASK, NULL, HFILL } },
		{ &hf_reliability,       { "Reliability parameter",     "rtcdc.reliability_parameter",   FT_UINT16,  BASE_DEC,  NULL,                      0x0,                                         NULL, HFILL } },
		{ &hf_priority,          { "Priority",                  "rtcdc.priority",                FT_UINT16,  BASE_DEC,  NULL,                      0x0,                                         NULL, HFILL } },
		{ &hf_label,             { "Label",                     "rtcdc.label",                   FT_STRING,  BASE_NONE, NULL,                      0x0,                                         NULL, HFILL } },
		{ &hf_error,             { "Error",                     "rtcdc.error",                   FT_UINT8,   BASE_DEC,  NULL,                      0x0,                                         NULL, HFILL } },
		{ &hf_sid,               { "Reverse stream identifier", "rtcdc.reverse_stream_id",       FT_UINT16,  BASE_DEC,  NULL,                      0x0,                                         NULL, HFILL } }
	};
	static gint *ett[] = {
		&ett_rtcdc,
		&ett_flags
	};

	proto_rtcdc = proto_register_protocol("WebRTC Datachannel Protocol", "RTCDC", "rtcdc");
	proto_register_field_array(proto_rtcdc, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));
	rtcdc_module = prefs_register_protocol(proto_rtcdc, proto_reg_handoff_rtcdc);
	prefs_register_uint_preference(rtcdc_module, "sctp.ppi", "RTCDC SCTP PPID", "RTCDC SCTP PPID if other than the default", 10, &rtcdc_ppid);
}

void
proto_reg_handoff_rtcdc(void)
{
	static gboolean initialized = FALSE;
	static dissector_handle_t rtcdc_handle;
	static guint32 current_ppid;

	if (!initialized) {
		rtcdc_handle = new_create_dissector_handle(dissect_rtcdc, proto_rtcdc);
		initialized = TRUE;
	} else {
		dissector_delete_uint("sctp.ppi", current_ppid, rtcdc_handle);
	}
	current_ppid = rtcdc_ppid;
	dissector_add_uint("sctp.ppi", current_ppid, rtcdc_handle);
}

/*
 * Editor modelines  -  http://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:
 */
