/*

 * packet-rtcdc.c

 * Routines for the RTCWeb Data Channel Protocol dissection

 * as specified in

 * https://tools.ietf.org/html/draft-jesup-rtcweb-data-protocol-03

 * and specified in

 * https://tools.ietf.org/html/draft-ietf-rtcweb-data-protocol-08

 * We might want to remove the support of

 * https://tools.ietf.org/html/draft-jesup-rtcweb-data-protocol-03

 * in the future, but I'll leave it in for now.

 * Copyright 2012 - 2013, Michael Tuexen <tuexen@wireshark.org>

 *

 * 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 <epan/expert.h>

#include <epan/prefs.h>

#include "packet-sctp.h"

void proto_register_rtcdc(void);

void proto_reg_handoff_rtcdc(void);

static dissector_handle_t rtcdc_handle;

/* Initialize the protocol and registered fields */

static int proto_rtcdc;

static int hf_message_type;

static int hf_channel_type;

static int hf_flags;

static int hf_flags_reserved;

static int hf_unordered_allowed;

static int hf_reliability;

static int hf_priority;

static int hf_label;

static int hf_error;

static int hf_sid;

static int hf_new_channel_type;

static int hf_new_reliability;

static int hf_new_priority;

static int hf_new_label_length;

static int hf_new_protocol_length;

static int hf_new_label;

static int hf_new_protocol;

/* Initialize the subtree pointers */

static int ett_rtcdc;

static int ett_flags;

static expert_field ei_rtcdc_new_reliability_non_zero;

static expert_field ei_rtcdc_message_type_unknown;

static expert_field ei_rtcdc_inconsistent_label_and_parameter_length;

static expert_field ei_rtcdc_message_too_long;

static expert_field ei_rtcdc_new_channel_type;

#define DATA_CHANNEL_OPEN_REQUEST     0x00

#define DATA_CHANNEL_OPEN_RESPONSE    0x01

#define DATA_CHANNEL_ACK              0x02

#define DATA_CHANNEL_NEW_OPEN_REQUEST 0x03

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"           },

    { DATA_CHANNEL_NEW_OPEN_REQUEST, "DATA_CHANNEL_OPEN_REQUEST"  },

    { 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_ASCII);

    }

    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_reported_length(tvb) > DATA_CHANNEL_RESPONSE_LENGTH) {

        expert_add_info(pinfo, rtcdc_item, &ei_rtcdc_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_reported_length(tvb) > DATA_CHANNEL_ACK_LENGTH) {

        expert_add_info(pinfo, rtcdc_item, &ei_rtcdc_message_too_long);

    }

    return;

}

#define NEW_DATA_CHANNEL_RELIABLE                          0x00

#define NEW_DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT           0x01

#define NEW_DATA_CHANNEL_PARTIAL_RELIABLE_TIMED            0x02

#define NEW_DATA_CHANNEL_RELIABLE_UNORDERED                0x80

#define NEW_DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED 0x81

#define NEW_DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED  0x82

static const value_string new_channel_type_values[] = {

    { NEW_DATA_CHANNEL_RELIABLE,                          "DATA_CHANNEL_RELIABLE"                          },

    { NEW_DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT,           "DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT"           },

    { NEW_DATA_CHANNEL_PARTIAL_RELIABLE_TIMED,            "DATA_CHANNEL_PARTIAL_RELIABLE_TIMED"            },

    { NEW_DATA_CHANNEL_RELIABLE_UNORDERED,                "DATA_CHANNEL_RELIABLE_UNORDERED"                },

    { NEW_DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED, "DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED" },

    { NEW_DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED,  "DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED"  },

    { 0,                                                  NULL                                             }

};

#define NEW_MESSAGE_TYPE_LENGTH    1

#define NEW_CHANNEL_TYPE_LENGTH    1

#define NEW_PRIORITY_LENGTH        2

#define NEW_RELIABILITY_LENGTH     4

#define NEW_LABEL_LENGTH_LENGTH    2

#define NEW_PROTOCOL_LENGTH_LENGTH 2

#define NEW_OPEN_REQUEST_HEADER_LENGTH (unsigned)(NEW_MESSAGE_TYPE_LENGTH + \

                                               NEW_CHANNEL_TYPE_LENGTH + \

                                               NEW_PRIORITY_LENGTH +    \

                                               NEW_RELIABILITY_LENGTH + \

                                               NEW_LABEL_LENGTH_LENGTH + \

                                               NEW_PROTOCOL_LENGTH_LENGTH)

#define NEW_MESSAGE_TYPE_OFFSET    0

#define NEW_CHANNEL_TYPE_OFFSET    (NEW_MESSAGE_TYPE_OFFSET + NEW_MESSAGE_TYPE_LENGTH)

#define NEW_PRIORITY_OFFSET        (NEW_CHANNEL_TYPE_OFFSET + NEW_CHANNEL_TYPE_LENGTH)

#define NEW_RELIABILITY_OFFSET     (NEW_PRIORITY_OFFSET + NEW_PRIORITY_LENGTH)

#define NEW_LABEL_LENGTH_OFFSET    (NEW_RELIABILITY_OFFSET + NEW_RELIABILITY_LENGTH)

#define NEW_PROTOCOL_LENGTH_OFFSET (NEW_LABEL_LENGTH_OFFSET + NEW_LABEL_LENGTH_LENGTH)

#define NEW_LABEL_OFFSET           (NEW_PROTOCOL_LENGTH_OFFSET + NEW_PROTOCOL_LENGTH_LENGTH)

static void

dissect_new_open_request_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *rtcdc_tree, proto_item *rtcdc_item)

{

    uint8_t channel_type;

    uint32_t reliability;

    uint16_t label_length;

    uint16_t protocol_length;

    channel_type = tvb_get_uint8(tvb, NEW_CHANNEL_TYPE_OFFSET);

    if ((channel_type & 0x7f) > 0x02) {

        expert_add_info(pinfo, rtcdc_item, &ei_rtcdc_new_channel_type);

    }

    reliability = tvb_get_ntohl(tvb, NEW_RELIABILITY_OFFSET);

    if ((reliability > 0) && ((channel_type & 0x7f) == 0x00)) {

        expert_add_info(pinfo, rtcdc_item, &ei_rtcdc_new_reliability_non_zero);

    }

    label_length = tvb_get_ntohs(tvb, NEW_LABEL_LENGTH_OFFSET);

    protocol_length = tvb_get_ntohs(tvb, NEW_PROTOCOL_LENGTH_OFFSET);

    if (NEW_OPEN_REQUEST_HEADER_LENGTH + (unsigned)label_length + (unsigned)protocol_length != tvb_reported_length(tvb)) {

        expert_add_info(pinfo, rtcdc_item, &ei_rtcdc_inconsistent_label_and_parameter_length);

    }

    if (rtcdc_tree) {

        proto_tree_add_item(rtcdc_tree, hf_new_channel_type, tvb, NEW_CHANNEL_TYPE_OFFSET, NEW_CHANNEL_TYPE_LENGTH, ENC_BIG_ENDIAN);

        proto_tree_add_item(rtcdc_tree, hf_new_priority, tvb, NEW_PRIORITY_OFFSET, NEW_PRIORITY_LENGTH, ENC_BIG_ENDIAN);

        proto_tree_add_item(rtcdc_tree, hf_new_reliability, tvb, NEW_RELIABILITY_OFFSET, NEW_RELIABILITY_LENGTH, ENC_BIG_ENDIAN);

        proto_tree_add_item(rtcdc_tree, hf_new_label_length, tvb, NEW_LABEL_LENGTH_OFFSET, NEW_LABEL_LENGTH_LENGTH, ENC_BIG_ENDIAN);

        proto_tree_add_item(rtcdc_tree, hf_new_protocol_length, tvb, NEW_PROTOCOL_LENGTH_OFFSET, NEW_PROTOCOL_LENGTH_LENGTH, ENC_BIG_ENDIAN);

        proto_tree_add_item(rtcdc_tree, hf_new_label, tvb, NEW_LABEL_OFFSET, label_length, ENC_ASCII);

        proto_tree_add_item(rtcdc_tree, hf_new_protocol, tvb, NEW_LABEL_OFFSET + label_length, protocol_length, ENC_ASCII);

    }

    return;

}

static int

dissect_rtcdc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)

{

    proto_item *rtcdc_item, *msg_item;

    proto_tree *rtcdc_tree;

    uint8_t     message_type;

    message_type  = tvb_get_uint8(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"));

    rtcdc_item = proto_tree_add_item(tree, proto_rtcdc, tvb, 0, -1, ENC_NA);

    rtcdc_tree = proto_item_add_subtree(rtcdc_item, ett_rtcdc);

    msg_item   = proto_tree_add_item(rtcdc_tree, hf_message_type, tvb, MESSAGE_TYPE_OFFSET, MESSAGE_TYPE_LENGTH, ENC_BIG_ENDIAN);

    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;

        case DATA_CHANNEL_NEW_OPEN_REQUEST:

            dissect_new_open_request_message(tvb, pinfo, rtcdc_tree, rtcdc_item);

            break;

        default:

            expert_add_info(pinfo, msg_item, &ei_rtcdc_message_type_unknown);

            break;

    }

    return tvb_captured_length(tvb);

}

void

proto_register_rtcdc(void)

{

    expert_module_t *expert_rtcdc;

    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 }

        },

        { &hf_new_channel_type,

          { "Channel type", "rtcdc.channel_type",

            FT_UINT8, BASE_DEC, VALS(new_channel_type_values), 0x0,

            NULL, HFILL }

        },

        { &hf_new_reliability,

          { "Reliability parameter", "rtcdc.reliability_parameter",

            FT_UINT32, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_new_priority,

          { "Priority", "rtcdc.priority",

            FT_UINT16, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_new_label_length,

          { "Label length", "rtcdc.label_length",

            FT_UINT16, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_new_protocol_length,

          { "Protocol length", "rtcdc.protocol_length",

            FT_UINT16, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_new_label,

          { "Label", "rtcdc.label",

            FT_STRING, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_new_protocol,

          { "Protocol", "rtcdc.protocol",

            FT_STRING, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        }

    };

    static int *ett[] = {

        &ett_rtcdc,

        &ett_flags

    };

    static ei_register_info ei[] = {

        { &ei_rtcdc_message_too_long, { "rtcdc.message_too_long", PI_MALFORMED, PI_ERROR, "Message too long", EXPFILL }},

        { &ei_rtcdc_new_channel_type, { "rtcdc.channel_type.unknown", PI_PROTOCOL, PI_WARN, "Unknown channel type", EXPFILL }},

        { &ei_rtcdc_new_reliability_non_zero, { "rtcdc.reliability_parameter.non_zero", PI_PROTOCOL, PI_WARN, "Reliability parameter non zero for reliable channel", EXPFILL }},

        { &ei_rtcdc_inconsistent_label_and_parameter_length, { "rtcdc.inconsistent_label_and_parameter_length", PI_MALFORMED, PI_ERROR, "Inconsistent label and parameter length", EXPFILL }},

        { &ei_rtcdc_message_type_unknown, { "rtcdc.message_type.unknown", PI_PROTOCOL, PI_WARN, "Unknown message type", EXPFILL }},

    };

    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));

    expert_rtcdc = expert_register_protocol(proto_rtcdc);

    expert_register_field_array(expert_rtcdc, ei, array_length(ei));

    /* rtcdc_module = prefs_register_protocol(proto_rtcdc, NULL); */

    rtcdc_handle = register_dissector("rtcdc", dissect_rtcdc, proto_rtcdc);

}

void

proto_reg_handoff_rtcdc(void)

{

    dissector_add_uint_with_preference("sctp.ppi", WEBRTC_DCEP_PROTOCOL_ID, rtcdc_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:

 */