/* packet-dccp.c
 * Routines for Datagram Congestion Control Protocol, "DCCP" dissection:
 * it should conform to RFC 4340
 *
 * Copyright 2005 _FF_
 *
 * Francesco Fondelli <francesco dot fondelli, gmail dot com>
 *
 * Copyright 2020-2021 by Thomas Dreibholz <dreibh [AT] simula.no>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * Copied from packet-udp.c
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

/* NOTES:
 *
 * Nov 13, 2006: makes checksum computation dependent
 * upon the header CsCov field (cf. RFC 4340, 5.1)
 * (Gerrit Renker)
 *
 * Nov 13, 2006: removes the case where checksums are zero
 * (unlike UDP/packet-udp, from which the code stems,
 * zero checksums are illegal in DCCP (as in TCP))
 * (Gerrit Renker)
 *
 * Jan 29, 2007: updates the offsets of the timestamps to be
 * compliant to (cf. RFC 4342, sec. 13).
 * (Gerrit Renker)
 *
 * Mar 11, 2012: add support for RFC 5596 (DCCP-Listen Packet)
 * (Francesco Fondelli)
 *
 * Feb 19, 2021: added service code types
 * (Thomas Dreibholz)
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/addr_resolv.h>
#include <epan/dccpservicecodes.h>
#include <epan/ipproto.h>
#include <epan/in_cksum.h>
#include <epan/prefs.h>
#include <epan/follow.h>
#include <epan/expert.h>
#include <epan/conversation.h>
#include <epan/conversation_table.h>
#include <epan/conversation_filter.h>
#include <epan/exported_pdu.h>
#include <epan/tap.h>
#include <wsutil/str_util.h>
#include <wsutil/utf8_entities.h>

#include "packet-dccp.h"

/*
 * Some definitions and the dissect_options() logic have been taken
 * from Arnaldo Carvalho de Melo's DCCP implementation, thanks!
 */
#define DCCP_GEN_HDR_LEN_NO_X 12      /* generic header length, without extended sequence numbers */
#define DCCP_GEN_HDR_LEN_X    16      /* generic header length, with extended sequence numbers */
#define DCCP_HDR_LEN 16               /* base DCCP header length, with 48 bits seqnums */
#define DCCP_HDR_LEN_MIN 12           /* with 24 bits seqnum */
#define DCCP_HDR_PKT_TYPES_LEN_MAX 12 /* max per packet type extra
                                       * header length
                                       */
#define DCCP_OPT_LEN_MAX 1008
#define DCCP_HDR_LEN_MAX (DCCP_HDR_LEN + DCCP_HDR_PKT_TYPES_LEN_MAX + \
                          DCCP_OPT_LEN_MAX)

/* Static DCCP flags. Set in dccp_flow_t:static_flags */
#define DCCP_S_BASE_SEQ_SET 0x01

void proto_register_dccp(void);
void proto_reg_handoff_dccp(void);

/*
 * FF: please keep this list in sync with
 * http://www.iana.org/assignments/dccp-parameters/dccp-parameters.xml
 * Registry Name: 'Packet Types'
 */
static const value_string dccp_packet_type_vals[] = {
    {0x0, "Request" },
    {0x1, "Response"},
    {0x2, "Data"    },
    {0x3, "Ack"     },
    {0x4, "DataAck" },
    {0x5, "CloseReq"},
    {0x6, "Close"   },
    {0x7, "Reset"   },
    {0x8, "Sync"    },
    {0x9, "SyncAck" },
    {0xA, "Listen"  },
    {0xB, "Reserved"},
    {0xC, "Reserved"},
    {0xD, "Reserved"},
    {0xE, "Reserved"},
    {0xF, "Reserved"},
    {0,   NULL      }
};

/*
 * Based on https://www.iana.org/assignments/service-codes/service-codes.xhtml
 * as of February 19th, 2021
 */
static const value_string dccp_service_code_vals[] = {
  { NOT_SPECIFIED_SERVICE_CODE, "not specified" },
  { LTP_SERVICE_CODE,           "LTP: Licklider Transmission Protocol" },
  { DISC_SERVICE_CODE,          "DISC: Discard" },
  { RTCP_SERVICE_CODE,          "RTCP: RTCP connection, separate from the corresponding RTP" },
  { RTPA_SERVICE_CODE,          "RTPA: RTP session conveying audio data (and associated RTCP)" },
  { RTPO_SERVICE_CODE,          "RTPO: RTP session conveying other media (and associated RTCP)" },
  { RTPT_SERVICE_CODE,          "RTPT: RTP session conveying text media (and associated RTCP)" },
  { RTPV_SERVICE_CODE,          "RTPV: RTP session conveying video data (and associated RTCP)" },
  { SYLG_SERVICE_CODE,          "SYLG: Syslog Protocol" },
  { BUNDLES_SERVICE_CODE,       "Bundle Protocol" },
  { NPMP_SERVICE_CODE,          "NPMP: NetPerfMeter Data" },
  { RESERVED_SERVICE_CODE,      "Reserved (Invalid)" },

  { 0,                          NULL } };

static const value_string dccp_reset_code_vals[] = {
    {0x00, "Unspecified"       },
    {0x01, "Closed"            },
    {0x02, "Aborted"           },
    {0x03, "No Connection"     },
    {0x04, "Packet Error"      },
    {0x05, "Option Error"      },
    {0x06, "Mandatory Error"   },
    {0x07, "Connection Refused"},
    {0x08, "Bad Service Code"  },
    {0x09, "Too Busy"          },
    {0x0A, "Bad Init Cookie"   },
    {0x0B, "Aggression Penalty"},
    {0x0C, "Reserved"          },
    {0,    NULL                }
};

static const range_string dccp_options_rvals[] = {
    {0x00, 0x00, "Padding" },
    {0x01, 0x01, "Mandatory" },
    {0x02, 0x02, "Slow Receiver" },
    {0x03, 0x1F, "Reserved"},
    {0x20, 0x20, "Change L" },
    {0x21, 0x21, "Confirm L"},
    {0x22, 0x22, "Change R" },
    {0x23, 0x23, "Confirm R"},
    {0x24, 0x24, "Init Cookie"},
    {0x25, 0x25, "NDP Count"},
    {0x26, 0x26, "Ack Vector [Nonce 0]"},
    {0x27, 0x27, "Ack Vector [Nonce 1]"},
    {0x28, 0x28, "Data Dropped"},
    {0x29, 0x29, "Timestamp"},
    {0x2A, 0x2A, "Timestamp Echo"},
    {0x2B, 0x2B, "Elapsed Time"},
    {0x2C, 0x2C, "Data checksum"},
    {0x2D, 0x7F, "Reserved"},
    {0x80, 0xBF, "CCID option"},
    {0xC0, 0xC0, "CCID3 Loss Event Rate"},
    {0xC1, 0xC1, "CCID3 Loss Intervals"},
    {0xC2, 0xC2, "CCID3 Receive Rate"},
    {0xC3, 0xFF, "CCID option"},
    {0, 0,   NULL}
};

static const range_string dccp_feature_numbers_rvals[] = {
    {0x00, 0x00, "Reserved" },
    {0x01, 0x01, "Congestion Control ID (CCID)" },
    {0x02, 0x02, "Allow Short Seqnums" },
    {0x03, 0x03, "Sequence Window" },
    {0x04, 0x04, "ECN Incapable" },
    {0x05, 0x05, "Ack Ratio" },
    {0x06, 0x06, "Send Ack Vector" },
    {0x07, 0x07, "Send NDP Count" },
    {0x08, 0x08, "Minimum Checksum Coverage" },
    {0x09, 0x09, "Check Data Checksum" },
    {0x03, 0x7F, "Reserved"},
    {0xC0, 0xC0, "Send Loss Event Rate"}, /* CCID3, RFC 4342, 8.5 */
    {0xC1, 0xFF, "CCID-specific feature"},
    {0, 0,   NULL}
};

static const unit_name_string units_bytes_sec = { "bytes/sec", NULL };

static int proto_dccp = -1;
static int dccp_tap = -1;
static int dccp_follow_tap = -1;

static int hf_dccp_srcport = -1;
static int hf_dccp_dstport = -1;
static int hf_dccp_port = -1;
static int hf_dccp_stream = -1;
static int hf_dccp_data_offset = -1;
static int hf_dccp_ccval = -1;
static int hf_dccp_cscov = -1;
static int hf_dccp_checksum = -1;
static int hf_dccp_checksum_status = -1;
static int hf_dccp_res1 = -1;
static int hf_dccp_type = -1;
static int hf_dccp_x = -1;
static int hf_dccp_res2 = -1;
static int hf_dccp_seq = -1;
static int hf_dccp_seq_abs = -1;

static int hf_dccp_ack_res = -1;
static int hf_dccp_ack = -1;
static int hf_dccp_ack_abs = -1;

static int hf_dccp_service_code = -1;
static int hf_dccp_reset_code = -1;
static int hf_dccp_data1 = -1;
static int hf_dccp_data2 = -1;
static int hf_dccp_data3 = -1;

static int hf_dccp_options = -1;
static int hf_dccp_option_type = -1;
static int hf_dccp_feature_number = -1;
static int hf_dccp_ndp_count = -1;
static int hf_dccp_timestamp = -1;
static int hf_dccp_timestamp_echo = -1;
static int hf_dccp_elapsed_time = -1;
static int hf_dccp_data_checksum = -1;

/* Generated from convert_proto_tree_add_text.pl */
static int hf_dccp_padding = -1;
static int hf_dccp_mandatory = -1;
static int hf_dccp_slow_receiver = -1;
static int hf_dccp_init_cookie = -1;
static int hf_dccp_ack_vector_nonce_0 = -1;
static int hf_dccp_ack_vector_nonce_1 = -1;
static int hf_dccp_data_dropped = -1;
static int hf_dccp_ccid3_loss_event_rate = -1;
static int hf_dccp_ccid3_loss_intervals = -1;
static int hf_dccp_ccid3_receive_rate = -1;
static int hf_dccp_option_reserved = -1;
static int hf_dccp_ccid_option_data = -1;
static int hf_dccp_option_unknown = -1;

static gint ett_dccp = -1;
static gint ett_dccp_options = -1;
static gint ett_dccp_options_item = -1;
static gint ett_dccp_feature = -1;

static expert_field ei_dccp_option_len_bad = EI_INIT;
static expert_field ei_dccp_advertised_header_length_bad = EI_INIT;
static expert_field ei_dccp_packet_type_reserved = EI_INIT;
static expert_field ei_dccp_checksum = EI_INIT;

static dissector_table_t dccp_subdissector_table;
static heur_dissector_list_t heur_subdissector_list;

/* preferences */
static gboolean dccp_summary_in_tree = TRUE;
static gboolean try_heuristic_first  = FALSE;
static gboolean dccp_check_checksum  = TRUE;
static gboolean dccp_relative_seq    = TRUE;
static guint32  dccp_stream_count;

static void
decode_dccp_ports(tvbuff_t *tvb, int offset, packet_info *pinfo,
                  proto_tree *tree, int sport, int dport)
{
    tvbuff_t *next_tvb;
    int       low_port, high_port;
    heur_dtbl_entry_t *hdtbl_entry;

    next_tvb = tvb_new_subset_remaining(tvb, offset);

    /* If the user has a "Follow DCCP Stream" window loading, pass a pointer
       to the payload tvb through the tap system. */
    if (have_tap_listener(dccp_follow_tap))
        tap_queue_packet(dccp_follow_tap, pinfo, next_tvb);

    /*
     * determine if this packet is part of a conversation and call dissector
     * for the conversation if available
     */
    if (try_conversation_dissector(&pinfo->src, &pinfo->dst, CONVERSATION_DCCP, sport,
                                   dport, next_tvb, pinfo, tree, NULL, 0)) {
        return;
    }

    if (try_heuristic_first) {
        /* do lookup with the heuristic subdissector table */
        if (dissector_try_heuristic(heur_subdissector_list, next_tvb, pinfo,
                                    tree, &hdtbl_entry, NULL)) {
            return;
        }
    }

    /*
     * Do lookups with the subdissector table.
     * We try the port number with the lower value first, followed by the
     * port number with the higher value.  This means that, for packets
     * where a dissector is registered for *both* port numbers:
     *
     * 1) we pick the same dissector for traffic going in both directions;
     *
     * 2) we prefer the port number that's more likely to be the right
     * one (as that prefers well-known ports to reserved ports);
     *
     * although there is, of course, no guarantee that any such strategy
     * will always pick the right port number.
     * XXX - we ignore port numbers of 0, as some dissectors use a port
     * number of 0 to disable the port.
     */
    if (sport > dport) {
        low_port  = dport;
        high_port = sport;
    } else {
        low_port  = sport;
        high_port = dport;
    }

    if (low_port != 0 &&
        dissector_try_uint(dccp_subdissector_table, low_port,
                           next_tvb, pinfo, tree)) {
        return;
    }

    if (high_port != 0 &&
        dissector_try_uint(dccp_subdissector_table, high_port,
                           next_tvb, pinfo, tree)) {
        return;
    }

    if (!try_heuristic_first) {
        /* do lookup with the heuristic subdissector table */
        if (dissector_try_heuristic(heur_subdissector_list, next_tvb,
                                    pinfo, tree, &hdtbl_entry, NULL)) {
            return;
        }
    }

    /* Oh, well, we don't know this; dissect it as data. */
    call_data_dissector(next_tvb, pinfo, tree);
}

/* Conversation and process code originally copied from packet-udp.c */
static struct dccp_analysis *
init_dccp_conversation_data(packet_info *pinfo)
{
  struct dccp_analysis *dccpd;

  /* Initialize the dccp protocol data structure to add to the dccp conversation */
  dccpd = wmem_new0(wmem_file_scope(), struct dccp_analysis);
  dccpd->flow1.static_flags = 0;
  dccpd->flow1.base_seq     = 0;
  dccpd->flow2.static_flags = 0;
  dccpd->flow2.base_seq     = 0;

  dccpd->stream   = dccp_stream_count++;
  dccpd->ts_first = pinfo->abs_ts;
  dccpd->ts_prev  = pinfo->abs_ts;

  return dccpd;
}

static struct dccp_analysis *
get_dccp_conversation_data(conversation_t *conv, packet_info *pinfo)
{
  int direction;
  struct dccp_analysis *dccpd;

  /* Get the data for this conversation */
  dccpd=(struct dccp_analysis *)conversation_get_proto_data(conv, proto_dccp);

  /* If the conversation was just created or it matched a
   * conversation with template options, dccpd will not
   * have been initialized. So, initialize
   * a new dccpd structure for the conversation.
   */
  if (!dccpd) {
    dccpd = init_dccp_conversation_data(pinfo);
    conversation_add_proto_data(conv, proto_dccp, dccpd);
  }

  /* check direction and get ua lists */
  direction=cmp_address(&pinfo->src, &pinfo->dst);
  /* if the addresses are equal, match the ports instead */
  if (direction == 0) {
    direction= (pinfo->srcport > pinfo->destport) ? 1 : -1;
  }
  if (direction >= 0) {
    dccpd->fwd=&(dccpd->flow1);
    dccpd->rev=&(dccpd->flow2);
  } else {
    dccpd->fwd=&(dccpd->flow2);
    dccpd->rev=&(dccpd->flow1);
  }

  return dccpd;
}

static const char* dccp_conv_get_filter_type(conv_item_t* conv, conv_filter_type_e filter)
{
    if (filter == CONV_FT_SRC_PORT)
        return "dccp.srcport";

    if (filter == CONV_FT_DST_PORT)
        return "dccp.dstport";

    if (filter == CONV_FT_ANY_PORT)
        return "dccp.port";

    if(!conv) {
        return CONV_FILTER_INVALID;
    }

    if (filter == CONV_FT_SRC_ADDRESS) {
        if (conv->src_address.type == AT_IPv4)
            return "ip.src";
        if (conv->src_address.type == AT_IPv6)
            return "ipv6.src";
    }

    if (filter == CONV_FT_DST_ADDRESS) {
        if (conv->dst_address.type == AT_IPv4)
            return "ip.dst";
        if (conv->dst_address.type == AT_IPv6)
            return "ipv6.dst";
    }

    if (filter == CONV_FT_ANY_ADDRESS) {
        if (conv->src_address.type == AT_IPv4)
            return "ip.addr";
        if (conv->src_address.type == AT_IPv6)
            return "ipv6.addr";
    }

    return CONV_FILTER_INVALID;
}

static ct_dissector_info_t dccp_ct_dissector_info = {&dccp_conv_get_filter_type};

static tap_packet_status
dccpip_conversation_packet(void *pct, packet_info *pinfo, epan_dissect_t *edt _U_, const void *vip, tap_flags_t flags)
{
    conv_hash_t *hash = (conv_hash_t*) pct;
    hash->flags = flags;
    const e_dccphdr *dccphdr=(const e_dccphdr *)vip;

    add_conversation_table_data_with_conv_id(hash, &dccphdr->ip_src, &dccphdr->ip_dst, dccphdr->sport, dccphdr->dport, (conv_id_t) dccphdr->stream, 1, pinfo->fd->pkt_len, &pinfo->rel_ts, &pinfo->abs_ts, &dccp_ct_dissector_info, CONVERSATION_DCCP);

    return TAP_PACKET_REDRAW;
}

static const char* dccp_endpoint_get_filter_type(endpoint_item_t* endpoint, conv_filter_type_e filter)
{

    if (filter == CONV_FT_SRC_PORT)
        return "dccp.srcport";

    if (filter == CONV_FT_DST_PORT)
        return "dccp.dstport";

    if (filter == CONV_FT_ANY_PORT)
        return "dccp.port";

    if(!endpoint) {
        return CONV_FILTER_INVALID;
    }


    if (filter == CONV_FT_SRC_ADDRESS) {
        if (endpoint->myaddress.type == AT_IPv4)
            return "ip.src";
        if (endpoint->myaddress.type == AT_IPv6)
            return "ipv6.src";
    }

    if (filter == CONV_FT_DST_ADDRESS) {
        if (endpoint->myaddress.type == AT_IPv4)
            return "ip.dst";
        if (endpoint->myaddress.type == AT_IPv6)
            return "ipv6.dst";
    }

    if (filter == CONV_FT_ANY_ADDRESS) {
        if (endpoint->myaddress.type == AT_IPv4)
            return "ip.addr";
        if (endpoint->myaddress.type == AT_IPv6)
            return "ipv6.addr";
    }

    return CONV_FILTER_INVALID;
}

static et_dissector_info_t dccp_endpoint_dissector_info = {&dccp_endpoint_get_filter_type};

static tap_packet_status
dccpip_endpoint_packet(void *pit, packet_info *pinfo, epan_dissect_t *edt _U_, const void *vip, tap_flags_t flags )
{
    conv_hash_t *hash = (conv_hash_t*) pit;
    hash->flags = flags;
    const e_dccphdr *dccphdr=(const e_dccphdr *)vip;

    /* Take two "add" passes per packet, adding for each direction, ensures that all
    packets are counted properly (even if address is sending to itself)
    XXX - this could probably be done more efficiently inside endpoint_table */
    add_endpoint_table_data(hash, &dccphdr->ip_src, dccphdr->sport, TRUE, 1, pinfo->fd->pkt_len, &dccp_endpoint_dissector_info, ENDPOINT_DCCP);
    add_endpoint_table_data(hash, &dccphdr->ip_dst, dccphdr->dport, FALSE, 1, pinfo->fd->pkt_len, &dccp_endpoint_dissector_info, ENDPOINT_DCCP);

    return TAP_PACKET_REDRAW;
}

/* Return the current stream count */
guint32 get_dccp_stream_count(void)
{
    return dccp_stream_count;
}

static gboolean
dccp_filter_valid(packet_info *pinfo)
{
    return proto_is_frame_protocol(pinfo->layers, "dccp");
}

static gchar*
dccp_build_filter(packet_info *pinfo)
{
    if( pinfo->net_src.type == AT_IPv4 && pinfo->net_dst.type == AT_IPv4 ) {
        /* DCCP over IPv4 */
        return ws_strdup_printf("(ip.addr eq %s and ip.addr eq %s) and (dccp.port eq %d and dccp.port eq %d)",
            address_to_str(pinfo->pool, &pinfo->net_src),
            address_to_str(pinfo->pool, &pinfo->net_dst),
            pinfo->srcport, pinfo->destport );
    }

    if( pinfo->net_src.type == AT_IPv6 && pinfo->net_dst.type == AT_IPv6 ) {
        /* DCCP over IPv6 */
        return ws_strdup_printf("(ipv6.addr eq %s and ipv6.addr eq %s) and (dccp.port eq %d and dccp.port eq %d)",
            address_to_str(pinfo->pool, &pinfo->net_src),
            address_to_str(pinfo->pool, &pinfo->net_dst),
            pinfo->srcport, pinfo->destport );
    }

    return NULL;
}

static gchar *dccp_follow_conv_filter(epan_dissect_t *edt _U_, packet_info *pinfo, guint *stream, guint *sub_stream _U_)
{
    conversation_t *conv;
    struct dccp_analysis *dccpd;

    /* XXX: Since DCCP doesn't use the endpoint API, we can only look
     * up using the current pinfo addresses and ports. We don't want
     * to create a new conversation or stream.
     * Eventually the endpoint API should support storing multiple
     * endpoints and DCCP should be changed to use the endpoint API.
     */
    if (((pinfo->net_src.type == AT_IPv4 && pinfo->net_dst.type == AT_IPv4) ||
        (pinfo->net_src.type == AT_IPv6 && pinfo->net_dst.type == AT_IPv6))
        && (pinfo->ptype == PT_DCCP) &&
        (conv=find_conversation(pinfo->num, &pinfo->net_src, &pinfo->net_dst, CONVERSATION_DCCP, pinfo->srcport, pinfo->destport, 0)) != NULL)
    {
        /* DCCP over IPv4/6 */
        dccpd = get_dccp_conversation_data(conv, pinfo);
        *stream = dccpd->stream;
        return ws_strdup_printf("dccp.stream eq %u", dccpd->stream);
    }

    return NULL;
}

static gchar *dccp_follow_index_filter(guint stream, guint sub_stream _U_)
{
    return ws_strdup_printf("dccp.stream eq %u", stream);
}

static gchar *dccp_follow_address_filter(address *src_addr, address *dst_addr, int src_port, int dst_port)
{
    const gchar  *ip_version = src_addr->type == AT_IPv6 ? "v6" : "";
    gchar         src_addr_str[WS_INET6_ADDRSTRLEN];
    gchar         dst_addr_str[WS_INET6_ADDRSTRLEN];

    address_to_str_buf(src_addr, src_addr_str, sizeof(src_addr_str));
    address_to_str_buf(dst_addr, dst_addr_str, sizeof(dst_addr_str));

    return ws_strdup_printf("((ip%s.src eq %s and dccp.srcport eq %d) and "
                     "(ip%s.dst eq %s and dccp.dstport eq %d))"
                     " or "
                     "((ip%s.src eq %s and dccp.srcport eq %d) and "
                     "(ip%s.dst eq %s and dccp.dstport eq %d))",
                     ip_version, src_addr_str, src_port,
                     ip_version, dst_addr_str, dst_port,
                     ip_version, dst_addr_str, dst_port,
                     ip_version, src_addr_str, src_port);
}

/*
 * decode a variable-length number of nbytes starting at offset.  Based on
 * a concept by Arnaldo de Melo
 */
static guint64
dccp_ntoh_var(tvbuff_t *tvb, gint offset, guint nbytes)
{
    guint64       value = 0;

    switch (nbytes)
    {
    case 5:
        value = tvb_get_ntoh40(tvb, offset);
        break;
    case 4:
        value = tvb_get_ntohl(tvb, offset);
        break;
    case 3:
        value = tvb_get_ntoh24(tvb, offset);
        break;
    case 2:
        value = tvb_get_ntohs(tvb, offset);
        break;
    case 1:
        value = tvb_get_guint8(tvb, offset);
        break;
    case 0:
        // do nothing
        break;
    case 6:
    default:
        value = tvb_get_ntoh48(tvb, offset);
        break;
    }

    return value;
}

static void
dissect_feature_options(proto_tree *dccp_options_tree, tvbuff_t *tvb,
                        int offset, guint8 option_len,
                        guint8 option_type)
{
    guint8      feature_number = tvb_get_guint8(tvb, offset);
    proto_item *dccp_item;
    proto_tree *feature_tree;
    int         i;

    feature_tree =
        proto_tree_add_subtree_format(dccp_options_tree, tvb, offset, option_len,
                            ett_dccp_feature, &dccp_item, "%s(",
                            rval_to_str_const(option_type, dccp_feature_numbers_rvals, "Unknown feature number"));

    proto_tree_add_uint(feature_tree, hf_dccp_feature_number, tvb,
                            offset, 1, feature_number);
    offset++;
    option_len--;

    /*
     * decode the feature according to whether it is server-priority (list)
     * or NN (single number)
     */
    switch (feature_number) {

    /* Server Priority features (RFC 4340, 6.3.1) */
    case 1:       /* Congestion Control ID (CCID); fall through    */
    case 2:       /* Allow Short Seqnums; fall through             */
    case 4:       /* ECN Incapable; fall through                   */
    case 6:       /* Send Ack Vector; fall through                 */
    case 7:       /* Send NDP Count; fall through                  */
    case 8:       /* Minimum Checksum Coverage; fall through       */
    case 9:       /* Check Data Checksum; fall through             */
    case 192:     /* Send Loss Event Rate, RFC 4342, section 8.4   */
        for (i = 0; i < option_len; i++)
            proto_item_append_text(dccp_item, "%s %d", i ? "," : "",
                                   tvb_get_guint8(tvb,
                                                  offset + i));
        break;

    /* Non-negotiable features (RFC 4340, 6.3.2) */

    case 3:       /* Sequence Window; fall through                 */
    case 5:       /* Ack Ratio                                     */

        if (option_len > 0) /* could be empty Confirm */
            proto_item_append_text(dccp_item, " %" PRIu64,
                                   dccp_ntoh_var(tvb, offset, option_len));
        break;

    /* Reserved, specific, or unknown features */
    default:
        proto_item_append_text(dccp_item, "%d", feature_number);
        break;
    }
    proto_item_append_text(dccp_item, ")");
}

/*
 * This function dissects DCCP options
 */
static void
dissect_options(tvbuff_t *tvb, packet_info *pinfo,
                proto_tree *dccp_options_tree, proto_tree *tree _U_,
                e_dccphdr *dccph _U_,
                int offset_start,
                int offset_end)
{
    /*
     * if here I'm sure there is at least offset_end - offset_start bytes
     * in tvb and it should be options
     */
    int         offset      = offset_start;
    guint8      option_type = 0;
    guint8      option_len  = 0;
    guint32     p;
    proto_item *option_item;
    proto_tree *option_tree;

    while (offset < offset_end) {
        /* first byte is the option type */
        option_type = tvb_get_guint8(tvb, offset);
        option_item =
            proto_tree_add_uint(dccp_options_tree, hf_dccp_option_type, tvb,
                                offset,
                                1,
                                option_type);

        if (option_type >= 32) { /* variable length options */
            option_len = tvb_get_guint8(tvb, offset+1);

            if (option_len < 2) {
                expert_add_info_format(pinfo, option_item, &ei_dccp_option_len_bad,
                    "Option length incorrect, must be >= 2");
                return;
            }

            proto_item_set_len(option_item, option_len);
            /* Remove the type and length fields out of length */
            offset += 2;
            option_len -= 2;
        } else { /* 1byte options */
            option_len = 1;
        }

        option_tree = proto_item_add_subtree(option_item, ett_dccp_options_item);
        switch (option_type) {
        case 0:
            proto_tree_add_item(option_tree, hf_dccp_padding, tvb, offset, option_len, ENC_NA);
            break;
        case 1:
            proto_tree_add_item(option_tree, hf_dccp_mandatory, tvb, offset, option_len, ENC_NA);
            break;
        case 2:
            proto_tree_add_item(option_tree, hf_dccp_slow_receiver, tvb, offset, option_len, ENC_NA);
            break;
        case 32:
        case 33:
        case 34:
        case 35:
            dissect_feature_options(option_tree, tvb, offset, option_len,
                                    option_type);
            break;
        case 36:
            proto_tree_add_item(option_tree, hf_dccp_init_cookie, tvb, offset, option_len, ENC_NA);
            break;
        case 37:
            if (option_len > 6)
                expert_add_info_format(pinfo, option_item, &ei_dccp_option_len_bad,
                                        "NDP Count too long (max 6 bytes)");
            else
                proto_tree_add_item(option_tree, hf_dccp_ndp_count, tvb, offset, option_len, ENC_BIG_ENDIAN);
            break;
        case 38:
            proto_tree_add_item(option_tree, hf_dccp_ack_vector_nonce_0, tvb, offset, option_len, ENC_NA);
            break;
        case 39:
            proto_tree_add_item(option_tree, hf_dccp_ack_vector_nonce_1, tvb, offset, option_len, ENC_NA);
            break;
        case 40:
            proto_tree_add_item(option_tree, hf_dccp_data_dropped, tvb, offset, option_len, ENC_NA);
            break;
        case 41:
            if (option_len == 4)
                proto_tree_add_item(option_tree, hf_dccp_timestamp, tvb,
                                    offset, 4, ENC_BIG_ENDIAN);
            else
                expert_add_info_format(pinfo, option_item, &ei_dccp_option_len_bad,
                                        "Timestamp too long [%u != 4]", option_len);
            break;
        case 42:
            if (option_len == 4)
                proto_tree_add_item(option_tree, hf_dccp_timestamp_echo,
                                    tvb, offset, 4, ENC_BIG_ENDIAN);
            else if (option_len == 6) {
                proto_tree_add_item(option_tree, hf_dccp_timestamp_echo,
                                    tvb, offset, 4, ENC_BIG_ENDIAN);
                proto_tree_add_item(option_tree, hf_dccp_elapsed_time,
                                    tvb, offset + 4, 2, ENC_BIG_ENDIAN);
            } else if (option_len == 8) {
                proto_tree_add_item(option_tree, hf_dccp_timestamp_echo,
                                    tvb, offset, 4, ENC_BIG_ENDIAN);
                proto_tree_add_item(option_tree, hf_dccp_elapsed_time,
                                    tvb, offset + 4, 4, ENC_BIG_ENDIAN);
            } else
                expert_add_info_format(pinfo, option_item, &ei_dccp_option_len_bad,
                                        "Wrong Timestamp Echo length");
            break;
        case 43:
            if (option_len == 2)
                proto_tree_add_item(option_tree, hf_dccp_elapsed_time,
                                    tvb, offset, 2, ENC_BIG_ENDIAN);
            else if (option_len == 4)
                proto_tree_add_item(option_tree, hf_dccp_elapsed_time,
                                    tvb, offset, 4, ENC_BIG_ENDIAN);
            else
                expert_add_info_format(pinfo, option_item, &ei_dccp_option_len_bad,
                                        "Wrong Elapsed Time length");
            break;
        case 44:
            if (option_len == 4) {
                proto_tree_add_item(option_tree, hf_dccp_data_checksum,
                                    tvb, offset, 4, ENC_BIG_ENDIAN);
            } else
                expert_add_info_format(pinfo, option_item, &ei_dccp_option_len_bad,
                                        "Wrong Data checksum length");
            break;
        case 192: /* RFC 4342, 8.5 */
            if (option_len == 4) {
                p = tvb_get_ntohl(tvb, offset);
                /*
                 * According to the comment in section 8.5 of RFC 4342,
                 * 0xffffffff can mean zero
                 */
                if (p == 0xFFFFFFFF)
                    proto_tree_add_uint_format_value(option_tree, hf_dccp_ccid3_loss_event_rate, tvb, offset,
                                        option_len, p, "0 (or max)");
                else
                    proto_tree_add_uint(option_tree, hf_dccp_ccid3_loss_event_rate, tvb, offset, option_len, p);
            } else
                expert_add_info_format(pinfo, option_item, &ei_dccp_option_len_bad,
                                        "Wrong CCID3 Loss Event Rate length");
            break;
        case 193: /* RFC 4342, 8.6 */
            proto_tree_add_item(dccp_options_tree, hf_dccp_ccid3_loss_intervals, tvb, offset, option_len, ENC_NA);
            /*
             * FIXME: not implemented and apparently not used by any
             * implementation so far
             */
            break;
        case 194: /* RFC 4342, 8.3 */
            if (option_len == 4)
                proto_tree_add_uint_format_value(option_tree, hf_dccp_ccid3_receive_rate, tvb, offset, option_len,
                                    tvb_get_ntohl(tvb, offset), "%u bytes/sec",
                                    tvb_get_ntohl(tvb, offset));
            else
                expert_add_info_format(pinfo, option_item, &ei_dccp_option_len_bad,
                                        "Wrong CCID3 Receive Rate length");
            break;
        default:
            if (((option_type >= 45) && (option_type <= 127)) ||
                ((option_type >= 3) && (option_type <= 31))) {
                proto_tree_add_item(option_tree, hf_dccp_option_reserved, tvb, offset, option_len, ENC_NA);
                break;
            }

            if (option_type >= 128) {
                proto_tree_add_bytes_format(option_tree, hf_dccp_ccid_option_data, tvb, offset, option_len,
                                    NULL, "CCID option %d", option_type);
                break;
            }

            /* if here we don't know this option */
            proto_tree_add_item(option_tree, hf_dccp_option_unknown, tvb, offset, option_len, ENC_NA);
            break;
        } /* end switch() */
        offset += option_len; /* move offset past the dissected option */
    } /* end while() */
}

/*
 * compute DCCP checksum coverage according to RFC 4340, section 9
*/
static inline guint
dccp_csum_coverage(const e_dccphdr *dccph, guint len)
{
    guint cov;

    if (dccph->cscov == 0)
        return len;

    cov = (dccph->data_offset + dccph->cscov - 1) * (guint)sizeof (guint32);
    return (cov > len) ? len : cov;
}

static int
dissect_dccp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
    proto_tree *dccp_tree;
    proto_item *item;
    proto_tree *dccp_options_tree = NULL;
    proto_item *dccp_item         = NULL;
    proto_item *hidden_item, *offset_item;
    vec_t      cksum_vec[4];
    guint32    phdr[2];
    guint      offset                     = 0;
    guint      len                        = 0;
    guint      reported_len               = 0;
    guint      csum_coverage_len;
    guint      advertised_dccp_header_len = 0;
    guint      options_len                = 0;
    guint64    seq;   /* Absolute or relative seq number (depending on DCCP_S_BASE_SEQ_SET) */
    guint64    ack;   /* Absolute or relative ack number (depending on DCCP_S_BASE_SEQ_SET) */
    e_dccphdr *dccph;
    conversation_t *conv = NULL;
    struct dccp_analysis *dccpd;

    dccph = wmem_new0(pinfo->pool, e_dccphdr);
    dccph->sport = tvb_get_ntohs(tvb, offset);
    dccph->dport = tvb_get_ntohs(tvb, offset + 2);
    copy_address_shallow(&dccph->ip_src, &pinfo->src);
    copy_address_shallow(&dccph->ip_dst, &pinfo->dst);

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "DCCP");
    col_clear(pinfo->cinfo, COL_INFO);
    col_append_ports(pinfo->cinfo, COL_INFO, PT_DCCP, dccph->sport, dccph->dport);

    dccp_item = proto_tree_add_item(tree, proto_dccp, tvb, offset, -1, ENC_NA);
    if (dccp_summary_in_tree) {
        proto_item_append_text(dccp_item, ", Src Port: %s, Dst Port: %s",
                               port_with_resolution_to_str(pinfo->pool, PT_DCCP, dccph->sport),
                               port_with_resolution_to_str(pinfo->pool, PT_DCCP, dccph->dport));
    }
    dccp_tree = proto_item_add_subtree(dccp_item, ett_dccp);

    proto_tree_add_item(dccp_tree, hf_dccp_srcport, tvb, offset, 2, ENC_BIG_ENDIAN);
    hidden_item = proto_tree_add_item(dccp_tree, hf_dccp_port, tvb, offset, 2, ENC_BIG_ENDIAN);
    proto_item_set_hidden(hidden_item);
    offset += 2;

    proto_tree_add_item(dccp_tree, hf_dccp_dstport, tvb, offset, 2, ENC_BIG_ENDIAN);
    hidden_item = proto_tree_add_item(dccp_tree, hf_dccp_port, tvb, offset, 2, ENC_BIG_ENDIAN);
    proto_item_set_hidden(hidden_item);
    offset += 2;

    /*
     * update pinfo structure. I guess I have to do it, because this
     * is a transport protocol dissector.
     */
    pinfo->ptype = PT_DCCP;
    pinfo->srcport = dccph->sport;
    pinfo->destport = dccph->dport;

    /* find (or create if needed) the conversation for this DCCP session */
    conv = find_or_create_conversation(pinfo);
    dccpd = get_dccp_conversation_data(conv, pinfo);
    item = proto_tree_add_uint(dccp_tree, hf_dccp_stream, tvb, offset, 0, dccpd->stream);
    proto_item_set_generated(item);

    /* Copy the stream index into the header as well to make it available
    * to tap listeners.
    */
    dccph->stream = dccpd->stream;

    dccph->data_offset = tvb_get_guint8(tvb, offset);
    advertised_dccp_header_len = dccph->data_offset * 4;
    offset_item = proto_tree_add_uint(dccp_tree, hf_dccp_data_offset, tvb, offset, 1,
                                      dccph->data_offset);
    offset += 1;

    dccph->cscov = tvb_get_guint8(tvb, offset) & 0x0F;
    dccph->ccval = tvb_get_guint8(tvb, offset) & 0xF0;
    dccph->ccval >>= 4;
    proto_tree_add_uint(dccp_tree, hf_dccp_ccval, tvb, offset, 1,
                        dccph->ccval);
    proto_tree_add_uint(dccp_tree, hf_dccp_cscov, tvb, offset, 1,
                        dccph->cscov);
    offset += 1;

    dccph->checksum = tvb_get_ntohs(tvb, offset);

    /*
     * checksum analysis taken from packet-udp (difference: mandatory
     * checksums in DCCP)
     */
    reported_len = tvb_reported_length(tvb);
    len = tvb_captured_length(tvb);
    csum_coverage_len = dccp_csum_coverage(dccph, reported_len);

    if (dccp_check_checksum && !pinfo->fragmented && len >= csum_coverage_len) {
        /* We're supposed to check the checksum, and the packet isn't part
         * of a fragmented datagram and isn't truncated, so we can checksum it.
         * XXX - make a bigger scatter-gather list once we do fragment
         * reassembly? */
        /* Set up the fields of the pseudo-header. */
        SET_CKSUM_VEC_PTR(cksum_vec[0], (const guint8 *)pinfo->src.data, pinfo->src.len);
        SET_CKSUM_VEC_PTR(cksum_vec[1], (const guint8 *)pinfo->dst.data, pinfo->dst.len);
        switch (pinfo->src.type) {
        case AT_IPv4:
            phdr[0] = g_htonl((IP_PROTO_DCCP << 16) + reported_len);
            SET_CKSUM_VEC_PTR(cksum_vec[2], (const guint8 *) &phdr, 4);
            break;
        case AT_IPv6:
            phdr[0] = g_htonl(reported_len);
            phdr[1] = g_htonl(IP_PROTO_DCCP);
            SET_CKSUM_VEC_PTR(cksum_vec[2], (const guint8 *) &phdr, 8);
            break;

        default:
            /* DCCP runs only atop IPv4 and IPv6... */
            DISSECTOR_ASSERT_NOT_REACHED();
            break;
        }
        SET_CKSUM_VEC_TVB(cksum_vec[3], tvb, 0, csum_coverage_len);
        proto_tree_add_checksum(dccp_tree, tvb, offset, hf_dccp_checksum, hf_dccp_checksum_status, &ei_dccp_checksum, pinfo, in_cksum(&cksum_vec[0], 4),
                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);
    } else {
        proto_tree_add_checksum(dccp_tree, tvb, offset, hf_dccp_checksum, hf_dccp_checksum_status, &ei_dccp_checksum, pinfo, 0,
                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
    }
    offset += 2;

    dccph->reserved1 = tvb_get_guint8(tvb, offset) & 0xE0;
    dccph->reserved1 >>= 5;
    hidden_item =
        proto_tree_add_uint(dccp_tree, hf_dccp_res1, tvb, offset, 1,
                            dccph->reserved1);
    proto_item_set_hidden(hidden_item);

    dccph->type = tvb_get_guint8(tvb, offset) & 0x1E;
    dccph->type >>= 1;
    proto_tree_add_uint(dccp_tree, hf_dccp_type, tvb, offset, 1,
                        dccph->type);
    if (dccp_summary_in_tree) {
        proto_item_append_text(dccp_item, " [%s]",
                               val_to_str_const(dccph->type, dccp_packet_type_vals,
                                                "Unknown Type"));
    }
    col_append_fstr(pinfo->cinfo, COL_INFO, " [%s]",
                    val_to_str_const(dccph->type, dccp_packet_type_vals,
                                     "Unknown Type"));

    dccph->x = tvb_get_guint8(tvb, offset) & 0x01;
    proto_tree_add_boolean(dccp_tree, hf_dccp_x, tvb, offset, 1,
                           dccph->x);
    offset += 1;

    if (dccph->x) {
        if (advertised_dccp_header_len < DCCP_GEN_HDR_LEN_X) {
            expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
                "Advertised header length (%u) is smaller than the minimum (%u)",
                advertised_dccp_header_len, DCCP_GEN_HDR_LEN_X);
            return tvb_reported_length(tvb);
        }
        dccph->reserved2 = tvb_get_guint8(tvb, offset);
        hidden_item =
            proto_tree_add_uint(dccp_tree, hf_dccp_res2, tvb, offset, 1,
                                dccph->reserved2);
        proto_item_set_hidden(hidden_item);
        offset += 1;

        dccph->seq = tvb_get_ntoh48(tvb, offset);
        if((dccp_relative_seq) && (dccpd->fwd->static_flags & DCCP_S_BASE_SEQ_SET)) {
            seq = dccph->seq - dccpd->fwd->base_seq;
            proto_tree_add_uint64_format_value(dccp_tree, hf_dccp_seq, tvb, offset, 6,
                                               seq, "%" PRIu64 "    (relative sequence number)", seq);
        }
        else {
            seq = dccph->seq;
        }
        proto_tree_add_uint64(dccp_tree, hf_dccp_seq_abs, tvb, offset, 6, dccph->seq);

        offset += 6;
    } else {
        if (advertised_dccp_header_len < DCCP_GEN_HDR_LEN_NO_X) {
            expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
                "Advertised header length (%u) is smaller than the minimum (%u)",
                advertised_dccp_header_len, DCCP_GEN_HDR_LEN_NO_X);
            return tvb_reported_length(tvb);
        }
        dccph->seq = tvb_get_ntoh24(tvb, offset);
        proto_tree_add_uint64(dccp_tree, hf_dccp_seq, tvb, offset, 3, dccph->seq);
        if((dccp_relative_seq) && (dccpd->fwd->static_flags & DCCP_S_BASE_SEQ_SET)) {
            seq = (dccph->seq - dccpd->fwd->base_seq) & 0xffffff;
            proto_tree_add_uint64_format_value(dccp_tree, hf_dccp_seq, tvb, offset, 3,
                                               seq, "%" PRIu64 "    (relative sequence number)", seq);
        }
        else {
            seq = dccph->seq;
        }
        offset += 3;
    }
    if (dccp_summary_in_tree) {
        proto_item_append_text(dccp_item, " Seq=%" PRIu64, seq);
    }
    col_append_fstr(pinfo->cinfo, COL_INFO, " Seq=%" PRIu64, seq);

    /* dissecting type dependent additional fields */
    switch (dccph->type) {
    case 0x0: /* DCCP-Request */
    case 0xA: /* DCCP-Listen */
        if (advertised_dccp_header_len < offset + 4) {
            expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
                "Advertised header length (%u) is smaller than the minimum (%u) for %s",
                advertised_dccp_header_len, offset + 4,
                val_to_str(dccph->type, dccp_packet_type_vals, "Unknown (%u)"));
            return tvb_reported_length(tvb);
        }
        dccph->service_code = tvb_get_ntohl(tvb, offset);
        if (tree)
            proto_tree_add_uint(dccp_tree, hf_dccp_service_code, tvb, offset, 4,
                                dccph->service_code);
        col_append_fstr(pinfo->cinfo, COL_INFO, " (service=%s)",
                        val_to_str(dccph->service_code, dccp_service_code_vals, "Unknown (%u)"));
        offset += 4; /* move offset past the service code */

        if( !(dccpd->fwd->static_flags & DCCP_S_BASE_SEQ_SET) ) {
            dccpd->fwd->base_seq = dccph->seq;
            dccpd->fwd->static_flags |= DCCP_S_BASE_SEQ_SET;
        }

        break;
    case 0x1: /* DCCP-Response */
        if (advertised_dccp_header_len < offset + 12) {
            expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
                "Advertised header length (%u) is smaller than the minimum (%u) for Response",
                advertised_dccp_header_len, offset + 12);
            return tvb_reported_length(tvb);
        }
        dccph->ack_reserved = tvb_get_ntohs(tvb, offset);
        if (tree) {
            hidden_item =
                proto_tree_add_uint(dccp_tree, hf_dccp_ack_res, tvb, offset, 2,
                                    dccph->ack_reserved);
            proto_item_set_hidden(hidden_item);
        }
        dccph->ack = tvb_get_ntohs(tvb, offset + 2);
        dccph->ack <<= 32;
        dccph->ack += tvb_get_ntohl(tvb, offset + 4);

        if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
            ack = dccph->ack - dccpd->rev->base_seq;
        }
        else {
            ack = dccph->ack;
        }

        if (tree) {
            if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
                proto_tree_add_uint64(dccp_tree, hf_dccp_ack, tvb, offset + 2, 6, ack);
            }
            proto_tree_add_uint64(dccp_tree, hf_dccp_ack_abs, tvb, offset + 2, 6, dccph->ack);
        }
        col_append_fstr(pinfo->cinfo, COL_INFO, " (Ack=%" PRIu64 ")", ack);
        offset += 8; /* move offset past the Acknowledgement Number Subheader */

        dccph->service_code = tvb_get_ntohl(tvb, offset);
        if (tree)
            proto_tree_add_uint(dccp_tree, hf_dccp_service_code, tvb, offset, 4,
                                dccph->service_code);
        col_append_fstr(pinfo->cinfo, COL_INFO, " (service=%s)",
                        val_to_str(dccph->service_code, dccp_service_code_vals, "Unknown (%u)"));

        offset += 4; /* move offset past the service code */

        if( !(dccpd->fwd->static_flags & DCCP_S_BASE_SEQ_SET) ) {
            dccpd->fwd->base_seq = dccph->seq;
            dccpd->fwd->static_flags |= DCCP_S_BASE_SEQ_SET;
        }

        break;
    case 0x2: /* DCCP-Data */
        /* nothing to dissect */
        break;
    case 0x3: /* DCCP-Ack */
    case 0x4: /* DCCP-DataAck */
        if (dccph->x) {
            if (advertised_dccp_header_len < offset + 8) {
                expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
                    "Advertised header length (%u) is smaller than the minimum (%u) for %s",
                    advertised_dccp_header_len, offset + 8,
                    val_to_str(dccph->type, dccp_packet_type_vals, "Unknown (%u)"));
                return tvb_reported_length(tvb);
            }
            dccph->ack_reserved = tvb_get_ntohs(tvb, offset);
            if (tree) {
                hidden_item =
                    proto_tree_add_uint(dccp_tree, hf_dccp_ack_res, tvb, offset,
                                        2, dccph->ack_reserved);
                proto_item_set_hidden(hidden_item);
            }
            dccph->ack = tvb_get_ntohs(tvb, offset + 2);
            dccph->ack <<= 32;
            dccph->ack += tvb_get_ntohl(tvb, offset + 4);

            if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
                ack = dccph->ack - dccpd->rev->base_seq;
            }
            else {
                ack = dccph->ack;
            }

            if (tree) {
                if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
                    proto_tree_add_uint64_format_value(dccp_tree, hf_dccp_ack, tvb, offset + 2, 6,
                                                       ack, "%" PRIu64 "    (relative acknowledgement number)", ack);
                }
                proto_tree_add_uint64(dccp_tree, hf_dccp_ack_abs, tvb, offset + 2, 6, dccph->ack);
            }
            col_append_fstr(pinfo->cinfo, COL_INFO, " (Ack=%" PRIu64 ")", ack);
            offset += 8; /* move offset past the Ack Number Subheader */
        } else {
            if (advertised_dccp_header_len < offset + 4) {
                expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
                    "Advertised header length (%u) is smaller than the minimum (%u) for %s",
                    advertised_dccp_header_len, offset + 4,
                    val_to_str(dccph->type, dccp_packet_type_vals, "Unknown (%u)"));
                return tvb_reported_length(tvb);
            }
            dccph->ack_reserved = tvb_get_guint8(tvb, offset);
            if (tree) {
                hidden_item =
                    proto_tree_add_uint(dccp_tree, hf_dccp_ack_res, tvb, offset,
                                        1, dccph->ack_reserved);
                proto_item_set_hidden(hidden_item);
            }
            dccph->ack = tvb_get_guint8(tvb, offset + 1);
            dccph->ack <<= 16;
            dccph->ack += tvb_get_ntohs(tvb, offset + 2);

            if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
                ack = (dccph->ack - dccpd->rev->base_seq) & 0xffffff;
            }
            else {
                ack = dccph->ack;
            }

            if (tree) {
                if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
                    proto_tree_add_uint64_format_value(dccp_tree, hf_dccp_ack, tvb, offset + 1, 3,
                                                       ack, "%" PRIu64 "    (relative acknowledgement number)", ack);
                }
                proto_tree_add_uint64(dccp_tree, hf_dccp_ack_abs, tvb, offset + 1, 3, dccph->ack);
            }
            col_append_fstr(pinfo->cinfo, COL_INFO, " (Ack=%" PRIu64 ")", ack);
            offset += 4; /* move offset past the Ack. Number Subheader */
        }
        break;
    case 0x7: /* DCCP-Reset */
        if (advertised_dccp_header_len < offset + 4) {
            expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
                "Advertised header length (%u) is smaller than the minimum (%u) for Reset",
                advertised_dccp_header_len, offset + 4);
            return tvb_reported_length(tvb);
        }
        dccph->ack_reserved = tvb_get_ntohs(tvb, offset);

        if (tree) {
            hidden_item =
                proto_tree_add_uint(dccp_tree, hf_dccp_ack_res, tvb, offset, 2,
                                    dccph->ack_reserved);
            proto_item_set_hidden(hidden_item);
        }

        dccph->ack = tvb_get_ntohs(tvb, offset + 2);
        dccph->ack <<= 32;
        dccph->ack += tvb_get_ntohl(tvb, offset + 4);

        if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
            ack = (dccph->ack - dccpd->rev->base_seq) & 0xffffff;
        }
        else {
            ack = dccph->ack;
        }

        if (tree) {
            if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
                proto_tree_add_uint64_format_value(dccp_tree, hf_dccp_ack, tvb, offset + 1, 3,
                                                    ack, "%" PRIu64 "    (relative acknowledgement number)", ack);
            }
            proto_tree_add_uint64(dccp_tree, hf_dccp_ack_abs, tvb, offset + 1, 3, dccph->ack);
        }
        col_append_fstr(pinfo->cinfo, COL_INFO, " (Ack=%" PRIu64 ")", ack);
        offset += 8; /* move offset past the Ack. Number Subheader */

        dccph->reset_code = tvb_get_guint8(tvb, offset);
        dccph->data1 = tvb_get_guint8(tvb, offset + 1);
        dccph->data2 = tvb_get_guint8(tvb, offset + 2);
        dccph->data3 = tvb_get_guint8(tvb, offset + 3);

        if (tree) {
            proto_tree_add_uint(dccp_tree, hf_dccp_reset_code, tvb, offset, 1,
                                dccph->reset_code);
            proto_tree_add_uint(dccp_tree, hf_dccp_data1, tvb, offset + 1, 1,
                                dccph->data1);
            proto_tree_add_uint(dccp_tree, hf_dccp_data2, tvb, offset + 2, 1,
                                dccph->data2);
            proto_tree_add_uint(dccp_tree, hf_dccp_data3, tvb, offset + 3, 1,
                                dccph->data3);
        }
        col_append_fstr(pinfo->cinfo, COL_INFO, " (code=%s)",
                        val_to_str_const(dccph->reset_code, dccp_reset_code_vals,
                                         "Unknown"));

        offset += 4; /* move offset past the Reset Code and data123 */
        break;
    case 0x5: /* DCCP-CloseReq */
    case 0x6: /* DCCP-Close */
    case 0x8: /* DCCP-Sync */
    case 0x9: /* DCCP-SyncAck */
        if (advertised_dccp_header_len < offset + 8) {
            expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
                "Advertised header length (%u) is smaller than the minimum (%u) for %s",
                advertised_dccp_header_len, offset + 8,
                val_to_str(dccph->type, dccp_packet_type_vals, "Unknown (%u)"));
            return tvb_reported_length(tvb);
        }
        dccph->ack_reserved = tvb_get_ntohs(tvb, offset);
        if (tree) {
            hidden_item =
                proto_tree_add_uint(dccp_tree, hf_dccp_ack_res, tvb, offset, 2,
                                    dccph->ack_reserved);
            proto_item_set_hidden(hidden_item);
        }
        dccph->ack = tvb_get_ntohs(tvb, offset + 2);
        dccph->ack <<= 32;
        dccph->ack += tvb_get_ntohl(tvb, offset + 4);

        if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
            ack = (dccph->ack - dccpd->rev->base_seq) & 0xffffff;
        }
        else {
            ack = dccph->ack;
        }

        if (tree) {
            if((dccp_relative_seq) && (dccpd->rev->static_flags & DCCP_S_BASE_SEQ_SET)) {
                proto_tree_add_uint64_format_value(dccp_tree, hf_dccp_ack, tvb, offset + 1, 3,
                                                    ack, "%" PRIu64 "    (relative acknowledgement number)", ack);
            }
            proto_tree_add_uint64(dccp_tree, hf_dccp_ack_abs, tvb, offset + 1, 3, dccph->ack);
        }
        col_append_fstr(pinfo->cinfo, COL_INFO, " (Ack=%" PRIu64 ")", ack);
        offset += 8; /* move offset past the Ack. Number Subheader */
        break;
    default:
        expert_add_info(pinfo, dccp_item, &ei_dccp_packet_type_reserved);
        return tvb_reported_length(tvb);
    }

    /*
     * note: data_offset is the offset from the start of the packet's
     * DCCP header to the start of its application data area, in 32-bit words.
     */
    if (advertised_dccp_header_len > DCCP_HDR_LEN_MAX) {
        expert_add_info_format(pinfo, offset_item, &ei_dccp_advertised_header_length_bad,
            "Advertised header length (%u) is larger than the maximum (%u)",
            advertised_dccp_header_len, DCCP_HDR_LEN_MAX);
        return tvb_reported_length(tvb);
    }

    /*
     * The checks done above ensure that
     * advertised_dccp_header_len >= offset.
     *
     * advertised_dccp_header_len - offset is the number of bytes of
     * options.
     */
    if (advertised_dccp_header_len > offset) {
        options_len = advertised_dccp_header_len - offset;
        if (dccp_tree) {
            dccp_item =
                proto_tree_add_none_format(dccp_tree, hf_dccp_options, tvb,
                                           offset,
                                           options_len, "Options: (%u byte%s)",
                                           options_len,
                                           plurality(options_len, "", "s"));
            dccp_options_tree = proto_item_add_subtree(dccp_item,
                                                       ett_dccp_options);
        }
        dissect_options(tvb, pinfo, dccp_options_tree, tree, dccph, offset,
                        offset + options_len);
    }

    offset += options_len; /* move offset past the Options */
    proto_item_set_end(dccp_item, tvb, offset);

    /* queuing tap data */
    tap_queue_packet(dccp_tap, pinfo, dccph);

    /* call sub-dissectors */
    if (!pinfo->flags.in_error_pkt || tvb_reported_length_remaining(tvb, offset) > 0)
        decode_dccp_ports(tvb, offset, pinfo, tree, dccph->sport, dccph->dport);

    return tvb_reported_length(tvb);
}

static void
dccp_init(void)
{
  dccp_stream_count = 0;
}

void
proto_register_dccp(void)
{
    module_t *dccp_module;

    static hf_register_info hf[] = {
        {
            &hf_dccp_srcport,
            {
                "Source Port", "dccp.srcport",
                FT_UINT16, BASE_PT_DCCP, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_dstport,
            {
                "Destination Port", "dccp.dstport",
                FT_UINT16, BASE_PT_DCCP, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_port,
            {
                "Source or Destination Port", "dccp.port",
                FT_UINT16, BASE_PT_DCCP, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_stream,
            {
                "Stream index", "dccp.stream",
                FT_UINT32, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_data_offset,
            {
                "Data Offset", "dccp.data_offset",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_ccval,
            {
                "CCVal", "dccp.ccval",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_cscov,
            {
                "Checksum Coverage", "dccp.cscov",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_checksum_status,
            {
                "Checksum Status", "dccp.checksum.status",
                FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_checksum,
            {
                "Checksum", "dccp.checksum",
                FT_UINT16, BASE_HEX, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_res1,
            {
                "Reserved", "dccp.res1",
                FT_UINT8, BASE_HEX, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_res2,
            {
                "Reserved", "dccp.res2",
                FT_UINT8, BASE_HEX, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_type,
            {
                "Type", "dccp.type",
                FT_UINT8, BASE_DEC, VALS(dccp_packet_type_vals), 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_x,
            {
                "Extended Sequence Numbers", "dccp.x",
                FT_BOOLEAN, BASE_NONE, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_seq,
            {
                "Sequence Number", "dccp.seq",
                FT_UINT64, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_seq_abs,
            {
                "Sequence Number (raw)", "dccp.seq_raw",
                FT_UINT64, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_ack_res,
            {
                "Reserved", "dccp.ack_res",
                FT_UINT16, BASE_HEX, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_ack,
            {
                "Acknowledgement Number", "dccp.ack",
                FT_UINT64, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_ack_abs,
            {
                "Acknowledgement Number (raw)", "dccp.ack_raw",
                FT_UINT64, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_service_code,
            {
                "Service Code", "dccp.service_code",
                FT_UINT32, BASE_DEC, VALS(dccp_service_code_vals), 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_reset_code,
            {
                "Reset Code", "dccp.reset_code",
                FT_UINT8, BASE_DEC, VALS(dccp_reset_code_vals), 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_data1,
            {
                "Data 1", "dccp.data1",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_data2,
            {
                "Data 2", "dccp.data2",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_data3,
            {
                "Data 3", "dccp.data3",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_option_type,
            {
                "Option Type", "dccp.option_type",
                FT_UINT8, BASE_DEC|BASE_RANGE_STRING, RVALS(dccp_options_rvals), 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_feature_number,
            {
                "Feature Number", "dccp.feature_number",
                FT_UINT8, BASE_DEC|BASE_RANGE_STRING, RVALS(dccp_feature_numbers_rvals), 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_ndp_count,
            {
                "NDP Count", "dccp.ndp_count",
                FT_UINT64, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_timestamp,
            {
                "Timestamp", "dccp.timestamp",
                FT_UINT32, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_timestamp_echo,
            {
                "Timestamp Echo", "dccp.timestamp_echo",
                FT_UINT32, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_elapsed_time,
            {
                "Elapsed Time", "dccp.elapsed_time",
                FT_UINT32, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_data_checksum,
            {
                "Data Checksum", "dccp.checksum_data",
                FT_UINT32, BASE_HEX, NULL, 0x0,
                NULL, HFILL
            }
        },
        {
            &hf_dccp_options,
            {
                "Options", "dccp.options",
                FT_NONE, BASE_NONE, NULL, 0x0,
                "DCCP Options fields", HFILL
            }
        },

        /* Generated from convert_proto_tree_add_text.pl */
        { &hf_dccp_padding, { "Padding", "dccp.padding", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_mandatory, { "Mandatory", "dccp.mandatory", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_slow_receiver, { "Slow Receiver", "dccp.slow_receiver", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_init_cookie, { "Init Cookie", "dccp.init_cookie", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_ack_vector_nonce_0, { "Ack Vector [Nonce 0]", "dccp.ack_vector.nonce_0", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_ack_vector_nonce_1, { "Ack Vector [Nonce 1]", "dccp.ack_vector.nonce_1", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_data_dropped, { "Data Dropped", "dccp.data_dropped", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_ccid3_loss_event_rate, { "CCID3 Loss Event Rate", "dccp.ccid3_loss_event_rate", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_ccid3_loss_intervals, { "CCID3 Loss Intervals", "dccp.ccid3_loss_intervals", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_ccid3_receive_rate, { "CCID3 Receive Rate", "dccp.ccid3_receive_rate", FT_UINT32, BASE_DEC|BASE_UNIT_STRING, &units_bytes_sec, 0x0, NULL, HFILL }},
        { &hf_dccp_option_reserved, { "Reserved", "dccp.option_reserved", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_ccid_option_data, { "CCID option", "dccp.ccid_option_data", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_dccp_option_unknown, { "Unknown", "dccp.option_unknown", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
    };

    static gint *ett[] = {
        &ett_dccp,
        &ett_dccp_options,
        &ett_dccp_options_item,
        &ett_dccp_feature
    };

    static ei_register_info ei[] = {
        { &ei_dccp_option_len_bad, { "dccp.option.len.bad", PI_PROTOCOL, PI_WARN, "Bad option length", EXPFILL }},
        { &ei_dccp_advertised_header_length_bad, { "dccp.advertised_header_length.bad", PI_MALFORMED, PI_ERROR, "Advertised header length bad", EXPFILL }},
        { &ei_dccp_packet_type_reserved, { "dccp.packet_type.reserved", PI_PROTOCOL, PI_WARN, "Reserved packet type: unable to dissect further", EXPFILL }},
        { &ei_dccp_checksum, { "dccp.bad_checksum", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }},
    };

    expert_module_t* expert_dccp;

    proto_dccp =
        proto_register_protocol("Datagram Congestion Control Protocol", "DCCP",
                                "dccp");
    proto_register_field_array(proto_dccp, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    expert_dccp = expert_register_protocol(proto_dccp);
    expert_register_field_array(expert_dccp, ei, array_length(ei));

    /* subdissectors */
    dccp_subdissector_table =
        register_dissector_table("dccp.port", "DCCP port", proto_dccp, FT_UINT16,
                                 BASE_DEC);
    heur_subdissector_list = register_heur_dissector_list("dccp", proto_dccp);

    /* reg preferences */
    dccp_module = prefs_register_protocol(proto_dccp, NULL);
    /* For reading older preference files with "dcp." preferences */
    prefs_register_module_alias("dcp", dccp_module);
    prefs_register_bool_preference(
        dccp_module, "summary_in_tree",
        "Show DCCP summary in protocol tree",
        "Whether the DCCP summary line should be shown in the protocol tree",
        &dccp_summary_in_tree);

    prefs_register_bool_preference(
        dccp_module, "try_heuristic_first",
        "Try heuristic sub-dissectors first",
        "Try to decode a packet using an heuristic sub-dissector before "
        "using a sub-dissector "
        "registered to a specific port",
        &try_heuristic_first);

    prefs_register_bool_preference(
        dccp_module, "check_checksum",
        "Check the validity of the DCCP checksum when possible",
        "Whether to check the validity of the DCCP checksum",
        &dccp_check_checksum);

    prefs_register_bool_preference(
        dccp_module, "relative_sequence_numbers",
        "Relative sequence numbers",
        "Make the DCCP dissector use relative sequence numbers instead of absolute ones.",
        &dccp_relative_seq);

    register_conversation_table(proto_dccp, FALSE, dccpip_conversation_packet, dccpip_endpoint_packet);
    register_conversation_filter("dccp", "DCCP", dccp_filter_valid, dccp_build_filter);
    register_follow_stream(proto_dccp, "dccp_follow", dccp_follow_conv_filter, dccp_follow_index_filter, dccp_follow_address_filter,
                           dccp_port_to_display, follow_tvb_tap_listener);

    register_init_routine(dccp_init);
}

void
proto_reg_handoff_dccp(void)
{
    dissector_handle_t dccp_handle;

    dccp_handle = create_dissector_handle(dissect_dccp, proto_dccp);
    dissector_add_uint("ip.proto", IP_PROTO_DCCP, dccp_handle);
    dccp_tap    = register_tap("dccp");
    dccp_follow_tap = register_tap("dccp_follow");
}

/*
 * 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:
 */
