/* packet-wcp.c

 * Routines for Wellfleet Compression frame disassembly

 * Copyright 2001, Jeffrey C. Foster <jfoste@woodward.com>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998

 *

 * SPDX-License-Identifier: GPL-2.0-or-later

 *

 * ToDo:

 *  Add preference to allow/disallow decompression

 *  Calculate and verify check byte (last byte), if only we knew how!

 *  Handle Wellfleet compression over PPP links.

 *    - This will require changing the sub-dissector call

 *      routine to determine if layer 2 is frame relay or

 *      or PPP and different sub-dissector routines for each.

 *

 * Based upon information in the Nortel TCL based Pcaptap code.

 *http://www.mynetworkforum.com/tools/PCAPTAP/pcaptap-Win32-3.00.exe

 *

 * And lzss algorithm

 *http://www.rasip.fer.hr/research/compress/algorithms/fund/lz/lzss.html

 */

/*

 * Wellfleet compression is a variation on LZSS encoding.

 *

 * Compression is done by keeping a sliding window of previous

 * data transmited. The sender will use a pattern match to

 * encode repeated data as a data pointer field. Then a stream

 * of pointers and actual data bytes. The pointer values include

 * an offset to previous data in the stream and the length of the

 *  matching data.

 *

 * The data pattern matching is done on the octets.

 *

 * The data is encoded as 8 field blocks with a compression flag

 * byte at the beginning.  If the bit is set in the compression

 * flag, then that field has a compression field. If it isn't set

 * then the byte is raw data.

 *

 * The compression field is either 2 or 3 bytes long. The length

 * is determined by the length of the matching data, for short

 * matches the match length is encoded in the high nibble of the

 * first byte. Otherwise the third byte of the field contains

 * the match length.

 *

 * First byte -

 * lower 4 bits:

 *    High order nibble of the offset

 *

 * upper 4 bits:

 *    1   = length is in 3rd byte

 *    2-F = length of matching data - 1

 *

 * Second byte -

 *  Lower byte of the source offset.

 *

 * Third byte -

 *  Length of match - 1 if First byte upper nibble = 1, otherwise

 *  this byte isn't added to data stream.

 *

 * Example:

 *  Uncompressed data (hex):  11 22 22 22 22 33 44 55 66 77

 *

 *

 *  Compression data :

 *      Flag bits:  0x20 (third field is compressed)

 *      Data: 11 22 20 00 33 44 55

 *        /  /  /  /

 *    raw data ------+--+  /  /

 *              (Comp length - 1)<<4+  /

 *    Data offset ----------+

 *

 *  Output data (hex):  20 11 22 20 00 33 44 55 66 77

 *

 * In this example the copy src is one byte behind the copy destination

 * so if appears as if output is being loaded with the source byte.

 *

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/proto_data.h>

#include <wiretap/wtap.h>

#include <wsutil/pint.h>

#include <epan/conversation.h>

#include <epan/etypes.h>

#include <epan/expert.h>

#include <epan/exceptions.h>

#include "packet-osi.h"

#define MAX_WIN_BUF_LEN 0x7fff    /* storage size for decompressed data */

#define MAX_WCP_BUF_LEN 2048    /* storage size for compressed data */

#define FROM_DCE  0x80    /* for direction setting */

void proto_register_wcp(void);

void proto_reg_handoff_wcp(void);

typedef struct {

  uint8_t *buf_cur;

  uint8_t buffer[MAX_WIN_BUF_LEN];

  /* initialized bytes in the buffer (since buf_cur may wrap around) */

  uint16_t initialized;

} wcp_window_t;

typedef struct {

  wcp_window_t recv;

  wcp_window_t send;

} wcp_circuit_data_t;

/* XXX do I really want the length in here */

typedef struct {

  uint16_t len;

  uint8_t buffer[MAX_WCP_BUF_LEN];

} wcp_pdata_t;

static int proto_wcp;

static int hf_wcp_cmd;

static int hf_wcp_ext_cmd;

static int hf_wcp_seq;

static int hf_wcp_chksum;

static int hf_wcp_tid;

static int hf_wcp_rev;

static int hf_wcp_init;

static int hf_wcp_seq_size;

static int hf_wcp_alg;

static int hf_wcp_alg_cnt;

static int hf_wcp_alg_a;

static int hf_wcp_alg_b;

static int hf_wcp_alg_c;

static int hf_wcp_alg_d;

/* static int hf_wcp_rexmit; */

static int hf_wcp_hist_size;

static int hf_wcp_ppc;

static int hf_wcp_pib;

static int hf_wcp_compressed_data;

static int hf_wcp_comp_bits;

/* static int hf_wcp_comp_marker; */

static int hf_wcp_short_len;

static int hf_wcp_long_len;

static int hf_wcp_short_run;

static int hf_wcp_long_run;

static int hf_wcp_offset;

static int ett_wcp;

static int ett_wcp_comp_data;

static int ett_wcp_field;

static expert_field ei_wcp_compressed_data_exceeds;

static expert_field ei_wcp_uncompressed_data_exceeds;

static expert_field ei_wcp_invalid_window_offset;

static expert_field ei_wcp_buffer_too_long;

/* static expert_field ei_wcp_invalid_match_length; */

static dissector_handle_t wcp_handle;

static dissector_handle_t fr_uncompressed_handle;

/*

 * Bits in the address field.

 */

#define WCP_CMD     0xf0  /* WCP Command */

#define WCP_EXT_CMD   0x0f  /* WCP Extended Command */

#define WCP_SEQ     0x0fff  /* WCP Sequence number */

#define WCP_OFFSET_MASK   0x0fff  /* WCP Pattern source offset */

#define PPC_COMPRESSED_IND    0x0

#define PPC_UNCOMPRESSED_IND    0x1

#define PPC_TPPC_COMPRESSED_IND   0x2

#define PPC_TPPC_UNCOMPRESSED_IND 0x3

#define CONNECT_REQ     0x4

#define CONNECT_ACK     0x5

#define CONNECT_NAK     0x6

#define DISCONNECT_REQ      0x7

#define DISCONNECT_ACK      0x8

#define INIT_REQ      0x9

#define INIT_ACK      0xa

#define RESET_REQ     0xb

#define RESET_ACK     0xc

#define REXMIT_NAK      0xd

static const value_string cmd_string[] = {

  {0, "Compressed Data"},

  {1, "Uncompressed Data"},

  {15, "Extended"},

  { 0,       NULL }

};

static const value_string ext_cmd_string[] = {

  {0, "Per Packet Compression"},

  {4, "Connect Req"},

  {5, "Connect Ack"},

  {9, "Init Req"},

  {0x0a, "Init Ack"},

  { 0,       NULL }

};

static tvbuff_t *wcp_uncompress(tvbuff_t *src_tvb, unsigned offset, packet_info *pinfo, proto_tree *tree);

static wcp_window_t *get_wcp_window_ptr(packet_info *pinfo);

static void

dissect_wcp_con_req(tvbuff_t *tvb, unsigned offset, proto_tree *tree) {

/* WCP connector request message */

  uint32_t alg_cnt;

  proto_tree_add_item(tree, hf_wcp_tid, tvb, offset, 2, ENC_BIG_ENDIAN);

  proto_tree_add_item(tree, hf_wcp_rev, tvb, offset + 2, 1, ENC_NA);

  proto_tree_add_item(tree, hf_wcp_init, tvb, offset + 3, 1, ENC_NA);

  proto_tree_add_item(tree, hf_wcp_seq_size, tvb, offset + 4, 1, ENC_NA);

  proto_tree_add_item_ret_uint(tree, hf_wcp_alg_cnt, tvb, offset + 5, 1, ENC_NA, &alg_cnt);

  proto_tree_add_item(tree, hf_wcp_alg_a, tvb, offset + 6, 1, ENC_NA);

  if (alg_cnt > 1)

    proto_tree_add_item(tree, hf_wcp_alg_b, tvb, offset + 7, 1, ENC_NA);

  if (alg_cnt > 2)

    proto_tree_add_item(tree, hf_wcp_alg_c, tvb, offset + 8, 1, ENC_NA);

  if (alg_cnt > 3)

    proto_tree_add_item(tree, hf_wcp_alg_d, tvb, offset + 9, 1, ENC_NA);

}

static void

dissect_wcp_con_ack(tvbuff_t *tvb, unsigned offset, proto_tree *tree) {

  /* WCP connector ack message */

  proto_tree_add_item(tree, hf_wcp_tid, tvb, offset, 2, ENC_BIG_ENDIAN);

  proto_tree_add_item(tree, hf_wcp_rev, tvb, offset + 2, 1, ENC_NA);

  proto_tree_add_item(tree, hf_wcp_seq_size, tvb, offset + 3, 1, ENC_NA);

  proto_tree_add_item(tree, hf_wcp_alg, tvb, offset + 4, 1, ENC_NA);

}

static void

dissect_wcp_init(tvbuff_t *tvb, unsigned offset, proto_tree *tree) {

  /* WCP Initiate Request/Ack message */

  proto_tree_add_item(tree, hf_wcp_tid, tvb, offset, 2, ENC_BIG_ENDIAN);

  proto_tree_add_item(tree, hf_wcp_rev, tvb, offset + 2, 1, ENC_NA);

  proto_tree_add_item(tree, hf_wcp_hist_size, tvb, offset + 3, 1, ENC_NA);

  proto_tree_add_item(tree, hf_wcp_ppc, tvb, offset + 4, 1, ENC_NA);

  proto_tree_add_item(tree, hf_wcp_pib, tvb, offset + 5, 1, ENC_NA);

}

static void

dissect_wcp_reset(tvbuff_t *tvb, unsigned offset, proto_tree *tree) {

  /* Process WCP Reset Request/Ack message */

  proto_tree_add_item(tree, hf_wcp_tid, tvb, offset, 2, ENC_BIG_ENDIAN);

}

static void wcp_save_data(tvbuff_t *tvb, packet_info *pinfo, proto_tree* tree) {

  wcp_window_t *buf_ptr = 0;

  size_t len;

  /* discard first 2 bytes, header and last byte (check byte) */

  len = tvb_reported_length(tvb) - 3;

  buf_ptr = get_wcp_window_ptr(pinfo);

  if ((buf_ptr->buf_cur + len) <= (buf_ptr->buffer + MAX_WIN_BUF_LEN)) {

    tvb_memcpy(tvb, buf_ptr->buf_cur, 2, len);

    buf_ptr->buf_cur += len;

  } else {

    uint8_t *buf_end = buf_ptr->buffer + MAX_WIN_BUF_LEN;

    tvb_memcpy(tvb, buf_ptr->buf_cur, 2, buf_end - buf_ptr->buf_cur);

    if (buf_ptr->buf_cur + len <= buf_end) {

      tvb_memcpy(tvb, buf_ptr->buffer, (int) (buf_end - buf_ptr->buf_cur-2),

        len - (buf_end - buf_ptr->buf_cur));

      buf_ptr->buf_cur += len - MAX_WIN_BUF_LEN;

    } else {

      proto_tree_add_expert_remaining(tree, pinfo, &ei_wcp_buffer_too_long, tvb, 0);

    }

  }

}

static int dissect_wcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) {

  proto_tree  *wcp_tree;

  proto_item  *ti;

  int   wcp_header_len;

  uint16_t    temp, cmd, ext_cmd, seq;

  tvbuff_t  *next_tvb;

  col_set_str(pinfo->cinfo, COL_PROTOCOL, "WCP");

  col_clear(pinfo->cinfo, COL_INFO);

  temp = tvb_get_ntohs(tvb, 0);

  cmd = (temp & 0xf000) >> 12;

  ext_cmd = (temp & 0x0f00) >> 8;

  if (cmd == 0xf)

    wcp_header_len = 1;

  else

    wcp_header_len = 2;

  seq = temp & 0x0fff;

  /* XXX should test seq to be sure it the last + 1 !! */

  col_set_str(pinfo->cinfo, COL_INFO, val_to_str_const(cmd, cmd_string, "Unknown"));

  if (cmd == 0xf)

    col_append_fstr(pinfo->cinfo, COL_INFO, ", %s",

        val_to_str_const(ext_cmd, ext_cmd_string, "Unknown"));

  ti = proto_tree_add_item(tree, proto_wcp, tvb, 0, wcp_header_len, ENC_NA);

  wcp_tree = proto_item_add_subtree(ti, ett_wcp);

  proto_tree_add_item(wcp_tree, hf_wcp_cmd, tvb, 0, 1, ENC_NA);

  if (cmd == 0xf) {

    proto_tree_add_item(wcp_tree, hf_wcp_ext_cmd, tvb, 1, 1, ENC_NA);

    switch (ext_cmd) {

    case CONNECT_REQ:

      dissect_wcp_con_req(tvb, 1, wcp_tree);

      break;

    case CONNECT_ACK:

      dissect_wcp_con_ack(tvb, 1, wcp_tree);

      break;

    case INIT_REQ:

    case INIT_ACK:

      dissect_wcp_init(tvb, 1, wcp_tree);

      break;

    case RESET_REQ:

    case RESET_ACK:

      dissect_wcp_reset(tvb, 1, wcp_tree);

      break;

    default:

      break;

    }

  } else {

    proto_tree_add_uint(wcp_tree, hf_wcp_seq, tvb, 0, 2, seq);

  }

  /* exit if done */

  if (cmd != 1 && cmd != 0 && !(cmd == 0xf && ext_cmd == 0))

    return 2;

  if (cmd == 1) { /* uncompressed data */

    if (!pinfo->fd->visited) { /* if first pass */

      wcp_save_data(tvb, pinfo, wcp_tree);

    }

    next_tvb = tvb_new_subset_remaining(tvb, wcp_header_len);

  } else { /* cmd == 0 || (cmd == 0xf && ext_cmd == 0) */

    next_tvb = wcp_uncompress(tvb, wcp_header_len, pinfo, wcp_tree);

    if (!next_tvb) {

      return tvb_captured_length(tvb);

    }

  }

  /* add the check byte */

  proto_tree_add_checksum(wcp_tree, tvb, tvb_reported_length(tvb) - 1, hf_wcp_chksum, -1, NULL, pinfo, 0, ENC_NA, PROTO_CHECKSUM_NO_FLAGS);

  call_dissector(fr_uncompressed_handle, next_tvb, pinfo, tree);

  return tvb_captured_length(tvb);

}

static uint8_t *

decompressed_entry(uint8_t *dst, uint16_t data_offset,

  uint16_t data_cnt, unsigned *len, wcp_window_t *buf_ptr)

{

  const uint8_t *src;

  uint8_t *buf_start, *buf_end;

  buf_start = buf_ptr->buffer;

  buf_end = buf_ptr->buffer + MAX_WIN_BUF_LEN;

  /* do the decompression for one field */

  src = (dst - 1 - data_offset);

  if (src < buf_start)

    src += MAX_WIN_BUF_LEN;

  /* XXX could do some fancy memory moves, later if speed is problem */

  while(data_cnt--) {

    *dst = *src;

    if (buf_ptr->initialized < MAX_WIN_BUF_LEN)

      buf_ptr->initialized++;

    if ( ++(*len) >MAX_WCP_BUF_LEN) {

      return NULL; /* end of buffer error */

    }

    if (dst++ == buf_end)

      dst = buf_start;

    if (src++ == buf_end)

      src = buf_start;

  }

  return dst;

}

static

wcp_window_t *get_wcp_window_ptr(packet_info *pinfo) {

  /* find the circuit for this DLCI, create one if needed */

  /* and return the wcp_window data structure pointer */

  /* for the direction of this packet */

  conversation_t *conv;

  wcp_circuit_data_t *wcp_circuit_data;

  conv = find_or_create_conversation(pinfo);

  wcp_circuit_data = (wcp_circuit_data_t *)conversation_get_proto_data(conv, proto_wcp);

  if (!wcp_circuit_data) {

    wcp_circuit_data = wmem_new0(wmem_file_scope(), wcp_circuit_data_t);

    wcp_circuit_data->recv.buf_cur = wcp_circuit_data->recv.buffer;

    wcp_circuit_data->send.buf_cur = wcp_circuit_data->send.buffer;

    conversation_add_proto_data(conv, proto_wcp, wcp_circuit_data);

  }

  if (pinfo->pseudo_header->dte_dce.flags & FROM_DCE)

    return &wcp_circuit_data->recv;

  else

    return &wcp_circuit_data->send;

}

static tvbuff_t *wcp_uncompress(tvbuff_t *src_tvb, unsigned offset, packet_info *pinfo, proto_tree *tree) {

  /* do the packet data uncompression and load it into the dst buffer */

  proto_tree  *cd_tree, *sub_tree;

  proto_item  *cd_item, *ti;

  unsigned len;

  int i;

  unsigned cnt = tvb_reported_length(src_tvb) - 1;/* don't include check byte */

  uint8_t *dst, *src, *buf_start, *buf_end, comp_flag_bits = 0;

  uint16_t data_offset, data_cnt;

  uint8_t src_buf[ MAX_WCP_BUF_LEN];

  tvbuff_t *tvb;

  wcp_window_t *buf_ptr = 0;

  wcp_pdata_t *pdata_ptr;

  buf_ptr = get_wcp_window_ptr(pinfo);

  buf_start = buf_ptr->buffer;

  buf_end = buf_start + MAX_WIN_BUF_LEN;

  cd_item = proto_tree_add_item(tree, hf_wcp_compressed_data,

    src_tvb, offset, cnt - offset, ENC_NA);

  cd_tree = proto_item_add_subtree(cd_item, ett_wcp_comp_data);

  if (cnt - offset > MAX_WCP_BUF_LEN) {

    expert_add_info_format(pinfo, cd_item, &ei_wcp_compressed_data_exceeds,

      "Compressed data exceeds maximum buffer length (%d > %d)",

      cnt - offset, MAX_WCP_BUF_LEN);

    return NULL;

  }

  /*

   * XXX - this will throw an exception if a snapshot length cut short

   * the data. We may want to try to dissect the data in that case,

   * and we may even want to try to decompress it, *but* we will

   * want to mark the buffer of decompressed data as incomplete, so

   * that we don't try to use it for decompressing later packets.

   */

  src = (uint8_t *)tvb_memcpy(src_tvb, src_buf, offset, cnt - offset);

  dst = buf_ptr->buf_cur;

  len = 0;

  i = -1;

  while(offset < cnt) {

    /* There are i bytes left for this byte of flag bits */

    if ( --i >= 0) {

      /*

       * There's still at least one more byte left for

       * the current set of compression flag bits; is

       * it compressed data or uncompressed data?

       */

      if (comp_flag_bits & 0x80) {

        /* This byte is compressed data */

        if (!(offset + 1 < cnt)) {

          /*

           * The data offset runs past the

           * end of the data.

           */

          return NULL;

        }

        data_offset = pntohu16(src) & WCP_OFFSET_MASK;

        if ((*src & 0xf0) == 0x10) {

          /*

           * The count of bytes to copy from

           * the dictionary window is in the

           * byte following the data offset.

           */

          if (!(offset + 2 < cnt)) {

            /*

             * The data count runs past the

             * end of the data.

             */

            return NULL;

          }

          data_cnt = *(src + 2) + 1;

          if (tree) {

            ti = proto_tree_add_item(cd_tree, hf_wcp_long_run, src_tvb,

               offset, 3, ENC_NA);

            sub_tree = proto_item_add_subtree(ti, ett_wcp_field);

            proto_tree_add_uint(sub_tree, hf_wcp_offset, src_tvb,

               offset, 2, data_offset);

            proto_tree_add_item(sub_tree, hf_wcp_long_len, src_tvb,

               offset+2, 1, ENC_BIG_ENDIAN);

          }

          src += 3;

          offset += 3;

        } else {

          /*

           * The count of bytes to copy from

           * the dictionary window is in

           * the upper 4 bits of the next

           * byte.

           */

          data_cnt = (*src >> 4) + 1;

          if (tree) {

            ti = proto_tree_add_item(cd_tree, hf_wcp_short_run, src_tvb,

               offset, 2, ENC_NA);

            sub_tree = proto_item_add_subtree(ti, ett_wcp_field);

            proto_tree_add_uint(sub_tree, hf_wcp_short_len, src_tvb,

               offset, 1, *src);

            proto_tree_add_uint(sub_tree, hf_wcp_offset, src_tvb,

               offset, 2, data_offset);

          }

          src += 2;

          offset += 2;

        }

        if (data_offset + 1 > buf_ptr->initialized) {

          expert_add_info_format(pinfo, cd_item, &ei_wcp_invalid_window_offset,

              "Data offset exceeds valid window size (%d > %d)",

              data_offset+1, buf_ptr->initialized);

          return NULL;

        }

        if (data_offset + 1 < data_cnt) {

          expert_add_info_format(pinfo, cd_item, &ei_wcp_invalid_window_offset,

              "Data count exceeds offset (%d > %d)",

              data_cnt, data_offset+1);

          return NULL;

        }

        if ( !pinfo->fd->visited) { /* if first pass */

          dst = decompressed_entry(dst,

            data_offset, data_cnt, &len,

            buf_ptr);

          if (dst == NULL) {

            expert_add_info_format(pinfo, cd_item, &ei_wcp_uncompressed_data_exceeds,

              "Uncompressed data exceeds maximum buffer length (%d > %d)",

              len, MAX_WCP_BUF_LEN);

            return NULL;

          }

        }

      }else {

        /*

         * This byte is uncompressed data; is there

         * room for it in the buffer of uncompressed

         * data?

         */

        if ( ++len >MAX_WCP_BUF_LEN) {

          /* No - report an error. */

          expert_add_info_format(pinfo, cd_item, &ei_wcp_uncompressed_data_exceeds,

            "Uncompressed data exceeds maximum buffer length (%d > %d)",

            len, MAX_WCP_BUF_LEN);

          return NULL;

        }

        if ( !pinfo->fd->visited) {

          /*

           * This is the first pass through

           * the packets, so copy it to the

           * buffer of uncompressed data.

           */

          *dst = *src;

          if (dst++ == buf_end)

            dst = buf_start;

          if (buf_ptr->initialized < MAX_WIN_BUF_LEN)

            buf_ptr->initialized++;

        }

        ++src;

        ++offset;

      }

      /* Skip to the next compression flag bit */

      comp_flag_bits <<= 1;

    }else {

      /*

       * There are no more bytes left for the current

       * set of compression flag bits, so this byte

       * is another byte of compression flag bits.

       */

      comp_flag_bits = *src++;

      proto_tree_add_uint(cd_tree, hf_wcp_comp_bits, src_tvb, offset, 1,

          comp_flag_bits);

      offset++;

      i = 8;

    }

  }

  if (pinfo->fd->visited) { /* if not first pass */

          /* get uncompressed data */

    pdata_ptr = (wcp_pdata_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_wcp, 0);

    if (!pdata_ptr) { /* exit if no data */

      REPORT_DISSECTOR_BUG("Can't find uncompressed data");

      return NULL;

    }

    len = pdata_ptr->len;

  } else {

    if (buf_ptr->buf_cur + len > buf_end) {

      expert_add_info_format(pinfo, cd_item, &ei_wcp_invalid_window_offset,

        "Uncompressed data exceeds available buffer length (%d > %d)",

        len, (int) (buf_end - buf_ptr->buf_cur));

      return NULL;

    }

    /* save the new data as per packet data */

    pdata_ptr = wmem_new0(wmem_file_scope(), wcp_pdata_t);

    memcpy( &pdata_ptr->buffer, buf_ptr->buf_cur, len);

    pdata_ptr->len = len;

    p_add_proto_data(wmem_file_scope(), pinfo, proto_wcp, 0, (void*)pdata_ptr);

    buf_ptr->buf_cur = dst;

  }

  tvb = tvb_new_child_real_data(src_tvb, pdata_ptr->buffer, pdata_ptr->len, pdata_ptr->len);

  /* Add new data to the data source list */

  add_new_data_source(pinfo, tvb, "Uncompressed WCP");

  return tvb;

}

void

proto_register_wcp(void)

{

  static hf_register_info hf[] = {

    { &hf_wcp_cmd,

      { "Command", "wcp.cmd", FT_UINT8, BASE_HEX, VALS(cmd_string), WCP_CMD,

        "Compression Command", HFILL }},

    { &hf_wcp_ext_cmd,

      { "Extended Command", "wcp.ext_cmd", FT_UINT8, BASE_HEX, VALS(ext_cmd_string), WCP_EXT_CMD,

        "Extended Compression Command", HFILL }},

    { &hf_wcp_seq,

      { "SEQ", "wcp.seq", FT_UINT16, BASE_HEX, NULL, WCP_SEQ,

        "Sequence Number", HFILL }},

    { &hf_wcp_chksum,

      { "Checksum", "wcp.checksum", FT_UINT8, BASE_DEC, NULL, 0,

        "Packet Checksum", HFILL }},

    { &hf_wcp_tid,

      { "TID", "wcp.tid", FT_UINT16, BASE_DEC, NULL, 0,

        NULL, HFILL }},

    { &hf_wcp_rev,

      { "Revision", "wcp.rev", FT_UINT8, BASE_DEC, NULL, 0,

        NULL, HFILL }},

    { &hf_wcp_init,

      { "Initiator", "wcp.init", FT_UINT8, BASE_DEC, NULL, 0,

        NULL, HFILL }},

    { &hf_wcp_seq_size,

      { "Seq Size", "wcp.seq_size", FT_UINT8, BASE_DEC, NULL, 0,

        "Sequence Size", HFILL }},

    { &hf_wcp_alg_cnt,

      { "Alg Count", "wcp.alg_cnt", FT_UINT8, BASE_DEC, NULL, 0,

        "Algorithm Count", HFILL }},

    { &hf_wcp_alg_a,

      { "Alg 1", "wcp.alg1", FT_UINT8, BASE_DEC, NULL, 0,

        "Algorithm #1", HFILL }},

    { &hf_wcp_alg_b,

      { "Alg 2", "wcp.alg2", FT_UINT8, BASE_DEC, NULL, 0,

        "Algorithm #2", HFILL }},

    { &hf_wcp_alg_c,

      { "Alg 3", "wcp.alg3", FT_UINT8, BASE_DEC, NULL, 0,

        "Algorithm #3", HFILL }},

    { &hf_wcp_alg_d,

      { "Alg 4", "wcp.alg4", FT_UINT8, BASE_DEC, NULL, 0,

        "Algorithm #4", HFILL }},

    { &hf_wcp_alg,

      { "Alg", "wcp.alg", FT_UINT8, BASE_DEC, NULL, 0,

        "Algorithm", HFILL }},

#if 0

    { &hf_wcp_rexmit,

      { "Rexmit", "wcp.rexmit", FT_UINT8, BASE_DEC, NULL, 0,

        "Retransmit", HFILL }},

#endif

    { &hf_wcp_hist_size,

      { "History", "wcp.hist", FT_UINT8, BASE_DEC, NULL, 0,

        "History Size", HFILL }},

    { &hf_wcp_ppc,

      { "PerPackComp", "wcp.ppc", FT_UINT8, BASE_DEC, NULL, 0,

        "Per Packet Compression", HFILL }},

    { &hf_wcp_pib,

      { "PIB", "wcp.pib", FT_UINT8, BASE_DEC, NULL, 0,

        NULL, HFILL }},

    { &hf_wcp_compressed_data,

      { "Compressed Data", "wcp.compressed_data", FT_NONE, BASE_NONE, NULL, 0,

        "Raw compressed data", HFILL }},

    { &hf_wcp_comp_bits,

      { "Compress Flag", "wcp.flag", FT_UINT8, BASE_HEX, NULL, 0,

        "Compressed byte flag", HFILL }},

#if 0

    { &hf_wcp_comp_marker,

      { "Compress Marker", "wcp.mark", FT_UINT8, BASE_DEC, NULL, 0,

        "Compressed marker", HFILL }},

#endif

    { &hf_wcp_offset,

      { "Source offset", "wcp.off", FT_UINT16, BASE_HEX, NULL, WCP_OFFSET_MASK,

        "Data source offset", HFILL }},

    { &hf_wcp_short_len,

      { "Compress Length", "wcp.short_len", FT_UINT8, BASE_HEX, NULL, 0xf0,

        "Compressed length", HFILL }},

    { &hf_wcp_long_len,

      { "Compress Length", "wcp.long_len", FT_UINT8, BASE_HEX, NULL, 0,

        "Compressed length", HFILL }},

    { &hf_wcp_long_run,

      { "Long Compression", "wcp.long_comp", FT_BYTES, BASE_NONE, NULL, 0,

        "Long Compression type", HFILL }},

    { &hf_wcp_short_run,

      { "Short Compression", "wcp.short_comp", FT_BYTES, BASE_NONE, NULL, 0,

        "Short Compression type", HFILL }},

  };

  static int *ett[] = {

    &ett_wcp,

    &ett_wcp_comp_data,

    &ett_wcp_field,

  };

  static ei_register_info ei[] = {

    { &ei_wcp_compressed_data_exceeds, { "wcp.compressed_data.exceeds", PI_MALFORMED, PI_ERROR, "Compressed data exceeds maximum buffer length", EXPFILL }},

    { &ei_wcp_uncompressed_data_exceeds, { "wcp.uncompressed_data.exceeds", PI_MALFORMED, PI_ERROR, "Uncompressed data exceeds maximum buffer length", EXPFILL }},

    { &ei_wcp_invalid_window_offset, { "wcp.off.invalid", PI_MALFORMED, PI_ERROR, "Offset points outside of visible window", EXPFILL }},

    { &ei_wcp_buffer_too_long, { "wcp.buffer_too_long", PI_MALFORMED, PI_ERROR, "Buffer too long", EXPFILL }},

#if 0

    { &ei_wcp_invalid_match_length, { "wcp.len.invalid", PI_MALFORMED, PI_ERROR, "Length greater than offset", EXPFILL }},

#endif

  };

  expert_module_t* expert_wcp;

  proto_wcp = proto_register_protocol ("Wellfleet Compression", "WCP", "wcp");

  proto_register_field_array (proto_wcp, hf, array_length(hf));

  proto_register_subtree_array(ett, array_length(ett));

  expert_wcp = expert_register_protocol(proto_wcp);

  expert_register_field_array(expert_wcp, ei, array_length(ei));

  wcp_handle = register_dissector("wcp", dissect_wcp, proto_wcp);

}

void

proto_reg_handoff_wcp(void) {

  /*

   * Get handle for the Frame Relay (uncompressed) dissector.

   */

  fr_uncompressed_handle = find_dissector_add_dependency("fr_uncompressed", proto_wcp);

  dissector_add_uint("fr.nlpid", NLPID_COMPRESSED, wcp_handle);

  dissector_add_uint("ethertype",  ETHERTYPE_WCP, wcp_handle);

}

/*

 * Editor modelines - https://www.wireshark.org/tools/modelines.html

 *

 * Local variables:

 * c-basic-offset: 8

 * tab-width: 8

 * indent-tabs-mode: t

 * End:

 *

 * vi: set shiftwidth=8 tabstop=8 noexpandtab:

 * :indentSize=8:tabSize=8:noTabs=false:

 */