2 * Routines for Wellfleet Compression frame disassembly
3 * Copyright 2001, Jeffrey C. Foster <jfoste@woodward.com>
7 * Wireshark - Network traffic analyzer
8 * By Gerald Combs <gerald@wireshark.org>
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version 2
14 * of the License, or (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
26 * Add preference to allow/disallow decompression
27 * Calculate and verify check byte (last byte), if only we knew how!
28 * Handle Wellfleet compression over PPP links.
29 * - This will require changing the sub-dissector call
30 * routine to determine if layer 2 is frame relay or
31 * or PPP and different sub-dissector routines for each.
33 * Based upon information in the Nortel TCL based Pcaptap code.
34 *http://www.mynetworkforum.com/tools/PCAPTAP/pcaptap-Win32-3.00.exe
37 *http://www.rasip.fer.hr/research/compress/algorithms/fund/lz/lzss.html
41 * Wellfleet compression is a variation on LZSS encoding.
43 * Compression is done by keeping a sliding window of previous
44 * data transmited. The sender will use a pattern match to
45 * encode repeated data as a data pointer field. Then a stream
46 * of pointers and actual data bytes. The pointer values include
47 * an offset to previous data in the stream and the length of the
50 * The data pattern matching is done on the octects.
52 * The data is encoded as 8 field blocks with a compression flag
53 * byte at the beginning. If the bit is set in the compression
54 * flag, then that field has a compression field. If it isn't set
55 * then the byte is raw data.
57 * The compression field is either 2 or 3 bytes long. The length
58 * is determined by the length of the matching data, for short
59 * matches the match length is encoded in the high nibble of the
60 * first byte. Otherwise the third byte of the field contains
65 * High order nibble of the offset
68 * 1 = length is in 3rd byte
69 * 2-F = length of matching data - 1
72 * Lower byte of the source offset.
75 * Length of match - 1 if First byte upper nibble = 1, otherwise
76 * this byte isn't added to data stream.
79 * Uncompressed data (hex): 11 22 22 22 22 33 44 55 66 77
83 * Flag bits: 0x20 (third field is compressed)
84 * Data: 11 22 20 00 33 44 55
86 * raw data ------+--+ / /
87 * (Comp length - 1)<<4+ /
88 * Data offset ----------+
90 * Output data (hex): 20 11 22 20 00 33 44 55 66 77
92 * In this example the copy src is one byte behind the copy destination
93 * so if appears as if output is being loaded with the source byte.
106 #include <epan/packet.h>
107 #include "packet-frame.h"
108 #include <epan/circuit.h>
109 #include <epan/emem.h>
110 #include <epan/etypes.h>
111 #include <epan/nlpid.h>
113 #define MAX_WIN_BUF_LEN 0x7fff /* storage size for decompressed data */
114 #define MAX_WCP_BUF_LEN 2048 /* storage size for decompressed data */
115 #define FROM_DCE 0x80 /* for direction setting */
120 guint8 buffer[MAX_WIN_BUF_LEN];
127 } wcp_circuit_data_t;
129 /*XXX do I really want the length in here */
133 guint8 buffer[MAX_WCP_BUF_LEN];
138 static int proto_wcp = -1;
139 static int hf_wcp_cmd = -1;
140 static int hf_wcp_ext_cmd = -1;
141 static int hf_wcp_seq = -1;
142 static int hf_wcp_chksum = -1;
143 static int hf_wcp_tid = -1;
144 static int hf_wcp_rev = -1;
145 static int hf_wcp_init = -1;
146 static int hf_wcp_seq_size = -1;
147 static int hf_wcp_alg = -1;
148 static int hf_wcp_alg_cnt = -1;
149 static int hf_wcp_alg_a = -1;
150 static int hf_wcp_alg_b = -1;
151 static int hf_wcp_alg_c = -1;
152 static int hf_wcp_alg_d = -1;
153 static int hf_wcp_rexmit = -1;
155 static int hf_wcp_hist_size = -1;
156 static int hf_wcp_ppc = -1;
157 static int hf_wcp_pib = -1;
159 static int hf_wcp_comp_bits = -1;
160 static int hf_wcp_comp_marker = -1;
161 static int hf_wcp_short_len = -1;
162 static int hf_wcp_long_len = -1;
163 static int hf_wcp_short_run = -1;
164 static int hf_wcp_long_run = -1;
165 static int hf_wcp_offset = -1;
167 static gint ett_wcp = -1;
168 static gint ett_wcp_field = -1;
170 static dissector_handle_t fr_uncompressed_handle;
173 * Bits in the address field.
175 #define WCP_CMD 0xf0 /* WCP Command */
176 #define WCP_EXT_CMD 0x0f /* WCP Extended Command */
177 #define WCP_SEQ 0x0fff /* WCP Sequence number */
178 #define WCP_OFFSET_MASK 0x0fff /* WCP Pattern source offset */
180 #define PPC_COMPRESSED_IND 0x0
181 #define PPC_UNCOMPRESSED_IND 0x1
182 #define PPC_TPPC_COMPRESSED_IND 0x2
183 #define PPC_TPPC_UNCOMPRESSED_IND 0x3
184 #define CONNECT_REQ 0x4
185 #define CONNECT_ACK 0x5
186 #define CONNECT_NAK 0x6
187 #define DISCONNECT_REQ 0x7
188 #define DISCONNECT_ACK 0x8
191 #define RESET_REQ 0xb
192 #define RESET_ACK 0xc
193 #define REXMIT_NAK 0xd
196 static const value_string cmd_string[] = {
197 {0, "Compressed Data"},
198 {1, "Uncompressed Data"},
203 static const value_string ext_cmd_string[] = {
204 {0, "Per Packet Compression"},
215 static tvbuff_t *wcp_uncompress( tvbuff_t *src_tvb, int offset, packet_info *pinfo, proto_tree *tree);
216 static wcp_window_t *get_wcp_window_ptr( packet_info *pinfo);
219 dissect_wcp_con_req(tvbuff_t *tvb, int offset, proto_tree *tree) {
221 /* WCP connector request message */
223 guint alg_cnt = tvb_get_guint8(tvb, 5);
225 proto_tree_add_uint(tree, hf_wcp_tid, tvb, offset, 2, tvb_get_ntohs(tvb, offset));
226 proto_tree_add_uint(tree, hf_wcp_rev, tvb, offset + 2, 1, tvb_get_guint8(tvb, offset + 2));
227 proto_tree_add_uint(tree, hf_wcp_init, tvb, offset + 3, 1, tvb_get_guint8(tvb, offset + 3));
228 proto_tree_add_uint(tree, hf_wcp_seq_size, tvb, offset + 4, 1, tvb_get_guint8(tvb, offset + 4));
229 proto_tree_add_uint(tree, hf_wcp_alg_cnt, tvb, offset + 5, 1, alg_cnt);
230 proto_tree_add_uint(tree, hf_wcp_alg_a, tvb, offset + 6, 1, tvb_get_guint8(tvb, offset + 6));
232 proto_tree_add_uint(tree, hf_wcp_alg_b, tvb, offset + 7, 1, tvb_get_guint8(tvb, offset + 7));
234 proto_tree_add_uint(tree, hf_wcp_alg_c, tvb, offset + 8, 1, tvb_get_guint8(tvb, offset + 8));
236 proto_tree_add_uint(tree, hf_wcp_alg_d, tvb, offset + 9, 1, tvb_get_guint8(tvb, offset + 9));
240 dissect_wcp_con_ack( tvbuff_t *tvb, int offset, proto_tree *tree){
242 /* WCP connector ack message */
244 proto_tree_add_uint(tree, hf_wcp_tid, tvb, offset, 2, tvb_get_ntohs(tvb, offset));
245 proto_tree_add_uint(tree, hf_wcp_rev, tvb, offset + 2, 1, tvb_get_guint8(tvb, offset + 2));
246 proto_tree_add_uint(tree, hf_wcp_seq_size, tvb, offset + 3, 1, tvb_get_guint8(tvb, offset + 3));
247 proto_tree_add_uint(tree, hf_wcp_alg, tvb, offset + 4, 1, tvb_get_guint8(tvb, offset + 4));
251 dissect_wcp_init( tvbuff_t *tvb, int offset, proto_tree *tree){
253 /* WCP Initiate Request/Ack message */
255 proto_tree_add_uint(tree, hf_wcp_tid, tvb, offset, 2, tvb_get_ntohs(tvb, offset));
256 proto_tree_add_uint(tree, hf_wcp_rev, tvb, offset + 2, 1, tvb_get_guint8(tvb, offset + 2));
257 proto_tree_add_uint(tree, hf_wcp_hist_size, tvb, offset + 3, 1, tvb_get_guint8(tvb, offset + 3));
258 proto_tree_add_uint(tree, hf_wcp_ppc, tvb, offset + 4, 1, tvb_get_guint8(tvb, offset + 4));
259 proto_tree_add_uint(tree, hf_wcp_pib, tvb, offset + 5, 1, tvb_get_guint8(tvb, offset + 5));
264 dissect_wcp_reset( tvbuff_t *tvb, int offset, proto_tree *tree){
266 /* Process WCP Reset Request/Ack message */
268 proto_tree_add_uint(tree, hf_wcp_tid, tvb, offset, 2, tvb_get_ntohs(tvb, offset));
272 static void wcp_save_data( tvbuff_t *tvb, packet_info *pinfo){
274 wcp_window_t *buf_ptr = 0;
277 /* discard first 2 bytes, header and last byte (check byte) */
278 len = tvb_reported_length( tvb)-3;
279 buf_ptr = get_wcp_window_ptr( pinfo);
281 if (( buf_ptr->buf_cur + len) <= (buf_ptr->buffer + MAX_WIN_BUF_LEN)){
282 tvb_memcpy( tvb, buf_ptr->buf_cur, 2, len);
283 buf_ptr->buf_cur = buf_ptr->buf_cur + len;
286 guint8 *buf_end = buf_ptr->buffer + MAX_WIN_BUF_LEN;
287 tvb_memcpy( tvb, buf_ptr->buf_cur, 2, buf_end - buf_ptr->buf_cur);
288 tvb_memcpy( tvb, buf_ptr->buffer, (gint) (buf_end - buf_ptr->buf_cur-2),
289 len - (buf_end - buf_ptr->buf_cur));
290 buf_ptr->buf_cur = buf_ptr->buf_cur + len - MAX_WIN_BUF_LEN;
296 static void dissect_wcp( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) {
298 proto_tree *wcp_tree;
301 guint16 temp, cmd, ext_cmd, seq;
304 col_set_str(pinfo->cinfo, COL_PROTOCOL, "WCP");
305 col_clear(pinfo->cinfo, COL_INFO);
307 temp =tvb_get_ntohs(tvb, 0);
309 cmd = (temp & 0xf000) >> 12;
310 ext_cmd = (temp & 0x0f00) >> 8;
319 /*XXX should test seq to be sure it the last + 1 !! */
321 if (check_col(pinfo->cinfo, COL_INFO)){
322 col_add_str(pinfo->cinfo, COL_INFO, val_to_str(cmd, cmd_string, "Unknown"));
324 col_append_fstr(pinfo->cinfo, COL_INFO, ", %s",
325 val_to_str(ext_cmd, ext_cmd_string, "Unknown"));
329 ti = proto_tree_add_item(tree, proto_wcp, tvb, 0, wcp_header_len, FALSE);
331 wcp_tree = proto_item_add_subtree(ti, ett_wcp);
333 proto_tree_add_uint(wcp_tree, hf_wcp_cmd, tvb, 0, 1, tvb_get_guint8( tvb, 0));
335 proto_tree_add_uint(wcp_tree, hf_wcp_ext_cmd, tvb, 1, 1,
336 tvb_get_guint8( tvb, 0));
339 dissect_wcp_con_req( tvb, 1, wcp_tree);
343 dissect_wcp_con_ack( tvb, 1, wcp_tree);
347 dissect_wcp_init( tvb, 1, wcp_tree);
351 dissect_wcp_reset( tvb, 1, wcp_tree);
357 proto_tree_add_uint(wcp_tree, hf_wcp_seq, tvb, 0, 2, seq);
366 if ( cmd != 1 && cmd != 0 && !(cmd == 0xf && ext_cmd == 0))
369 if ( cmd == 1) { /* uncompressed data */
370 if ( !pinfo->fd->flags.visited){ /* if first pass */
371 wcp_save_data( tvb, pinfo);
373 next_tvb = tvb_new_subset(tvb, wcp_header_len, -1, -1);
375 else { /* cmd == 0 || (cmd == 0xf && ext_cmd == 0) */
377 next_tvb = wcp_uncompress( tvb, wcp_header_len, pinfo, wcp_tree);
380 proto_tree_add_protocol_format(tree, proto_malformed, tvb, 0, 0,
381 "[Malformed Frame: Bad WCP compressed data]" );
386 if ( tree) /* add the check byte */
387 proto_tree_add_uint(wcp_tree, hf_wcp_chksum, tvb,
388 tvb_reported_length( tvb)-1, 1,
389 tvb_get_guint8( tvb, tvb_reported_length(tvb)-1));
391 call_dissector(fr_uncompressed_handle, next_tvb, pinfo, tree);
397 static guint8 *decompressed_entry( guint8 *src, guint8 *dst, int *len, guint8 * buf_start, guint8 *buf_end){
399 /* do the decompression for one field */
401 guint16 data_offset, data_cnt;
404 data_offset = (*(src++) & 0xf) << 8; /* get high byte */
405 data_offset += *(src++); /* add next byte */
407 if (( tmp & 0xf0) == 0x10){ /* 2 byte count */
411 }else { /* one byte count */
417 src = (dst - 1 - data_offset);
418 if ( src < buf_start)
419 src += MAX_WIN_BUF_LEN;
422 /*XXX could do some fancy memory moves, later if speed is problem */
426 if ( ++(*len) >MAX_WCP_BUF_LEN){
427 printf("decomp failed, len = %d\n", *len);
429 return NULL; /* end of buffer error */
431 if ( dst++ == buf_end)
433 if ( src++ == buf_end)
442 wcp_window_t *get_wcp_window_ptr( packet_info *pinfo){
444 /* find the circuit for this DLCI, create one if needed */
445 /* and return the wcp_window data structure pointer */
446 /* for the direction of this packet */
449 wcp_circuit_data_t *wcp_circuit_data;
451 circuit = find_circuit( pinfo->ctype, pinfo->circuit_id,
454 circuit = circuit_new( pinfo->ctype, pinfo->circuit_id,
457 wcp_circuit_data = circuit_get_proto_data(circuit, proto_wcp);
458 if ( !wcp_circuit_data){
459 wcp_circuit_data = se_alloc(sizeof(wcp_circuit_data_t));
460 wcp_circuit_data->recv.buf_cur = wcp_circuit_data->recv.buffer;
461 wcp_circuit_data->send.buf_cur = wcp_circuit_data->send.buffer;
462 circuit_add_proto_data(circuit, proto_wcp, wcp_circuit_data);
464 if (pinfo->pseudo_header->x25.flags & FROM_DCE)
465 return &wcp_circuit_data->recv;
467 return &wcp_circuit_data->send;
471 static tvbuff_t *wcp_uncompress( tvbuff_t *src_tvb, int offset, packet_info *pinfo, proto_tree *tree) {
473 /* do the packet data uncompression and load it into the dst buffer */
475 proto_tree *sub_tree;
479 int cnt = tvb_reported_length( src_tvb)-1; /* don't include check byte */
481 guint8 *dst, *src, *buf_start, *buf_end, comp_flag_bits = 0;
482 guint8 src_buf[ MAX_WCP_BUF_LEN];
483 tvbuff_t *volatile tvb = 0;
484 wcp_window_t *buf_ptr = 0;
485 wcp_pdata_t *volatile pdata_ptr;
486 volatile gboolean bounds_error = FALSE;
488 buf_ptr = get_wcp_window_ptr( pinfo);
490 buf_start = buf_ptr->buffer;
491 buf_end = buf_start + MAX_WIN_BUF_LEN;
493 if (cnt - offset > MAX_WCP_BUF_LEN) {
495 proto_tree_add_text( tree, src_tvb, offset, -1,
496 "Compressed data exceeds maximum buffer length (%d > %d)",
497 cnt - offset, MAX_WCP_BUF_LEN);
501 src = tvb_memcpy(src_tvb, src_buf, offset, cnt - offset);
502 dst = buf_ptr->buf_cur;
504 while( offset++ < cnt){
507 if ( comp_flag_bits & 0x80){ /* if this is a compressed entry */
509 if ( !pinfo->fd->flags.visited){ /* if first pass */
510 dst = decompressed_entry( src, dst, &len, buf_start, buf_end);
512 if ((*src & 0xf0) == 0x10){
514 ti = proto_tree_add_item( tree, hf_wcp_long_run, src_tvb,
516 sub_tree = proto_item_add_subtree(ti, ett_wcp_field);
517 proto_tree_add_uint(sub_tree, hf_wcp_offset, src_tvb,
518 offset-1, 2, pntohs(src));
520 proto_tree_add_item( sub_tree, hf_wcp_long_len, src_tvb,
521 offset+1, 1, pntohs(src));
527 ti = proto_tree_add_item( tree, hf_wcp_short_run, src_tvb,
528 offset - 1, 2, *src);
529 sub_tree = proto_item_add_subtree(ti, ett_wcp_field);
530 proto_tree_add_item( sub_tree, hf_wcp_short_len, src_tvb,
532 proto_tree_add_uint(sub_tree, hf_wcp_offset, src_tvb,
533 offset-1, 2, pntohs(src));
539 if ( !pinfo->fd->flags.visited){ /* if first pass */
541 if ( dst++ == buf_end)
549 if ( len >MAX_WCP_BUF_LEN){
553 comp_flag_bits <<= 1;
555 }else { /* compressed data flag */
557 comp_flag_bits = *src++;
559 proto_tree_add_uint( tree, hf_wcp_comp_bits, src_tvb, offset-1, 1,
566 if ( pinfo->fd->flags.visited){ /* if not first pass */
567 /* get uncompressed data */
568 pdata_ptr = p_get_proto_data( pinfo->fd, proto_wcp);
570 if ( !pdata_ptr) /* exit if no data */
572 len = pdata_ptr->len;
575 /* save the new data as per packet data */
576 pdata_ptr = se_alloc(sizeof(wcp_pdata_t));
577 memcpy( &pdata_ptr->buffer, buf_ptr->buf_cur, len);
578 pdata_ptr->len = len;
580 p_add_proto_data( pinfo->fd, proto_wcp, (void*)pdata_ptr);
582 buf_ptr->buf_cur = dst;
587 tvb = tvb_new_child_real_data(src_tvb, pdata_ptr->buffer, pdata_ptr->len, pdata_ptr->len);
590 DISSECTOR_ASSERT_NOT_REACHED();
592 CATCH(ReportedBoundsError) {
597 if (bounds_error) return NULL;
599 /* Add new data to the data source list */
600 add_new_data_source( pinfo, tvb, "Uncompressed WCP");
607 proto_register_wcp(void)
609 static hf_register_info hf[] = {
611 { "Command", "wcp.cmd", FT_UINT8, BASE_HEX, VALS(cmd_string), WCP_CMD,
612 "Compression Command", HFILL }},
614 { "Extended Command", "wcp.ext_cmd", FT_UINT8, BASE_HEX, VALS(ext_cmd_string), WCP_EXT_CMD,
615 "Extended Compression Command", HFILL }},
617 { "SEQ", "wcp.seq", FT_UINT16, BASE_HEX, NULL, WCP_SEQ,
618 "Sequence Number", HFILL }},
620 { "Checksum", "wcp.checksum", FT_UINT8, BASE_DEC, NULL, 0,
621 "Packet Checksum", HFILL }},
623 { "TID", "wcp.tid", FT_UINT16, BASE_DEC, NULL, 0,
626 { "Revision", "wcp.rev", FT_UINT8, BASE_DEC, NULL, 0,
629 { "Initiator", "wcp.init", FT_UINT8, BASE_DEC, NULL, 0,
632 { "Seq Size", "wcp.seq_size", FT_UINT8, BASE_DEC, NULL, 0,
633 "Sequence Size", HFILL }},
635 { "Alg Count", "wcp.alg_cnt", FT_UINT8, BASE_DEC, NULL, 0,
636 "Algorithm Count", HFILL }},
638 { "Alg 1", "wcp.alg1", FT_UINT8, BASE_DEC, NULL, 0,
639 "Algorithm #1", HFILL }},
641 { "Alg 2", "wcp.alg2", FT_UINT8, BASE_DEC, NULL, 0,
642 "Algorithm #2", HFILL }},
644 { "Alg 3", "wcp.alg3", FT_UINT8, BASE_DEC, NULL, 0,
645 "Algorithm #3", HFILL }},
647 { "Alg 4", "wcp.alg4", FT_UINT8, BASE_DEC, NULL, 0,
648 "Algorithm #4", HFILL }},
650 { "Alg", "wcp.alg", FT_UINT8, BASE_DEC, NULL, 0,
651 "Algorithm", HFILL }},
653 { "Rexmit", "wcp.rexmit", FT_UINT8, BASE_DEC, NULL, 0,
654 "Retransmit", HFILL }},
656 { "History", "wcp.hist", FT_UINT8, BASE_DEC, NULL, 0,
657 "History Size", HFILL }},
659 { "PerPackComp", "wcp.ppc", FT_UINT8, BASE_DEC, NULL, 0,
660 "Per Packet Compression", HFILL }},
662 { "PIB", "wcp.pib", FT_UINT8, BASE_DEC, NULL, 0,
665 { "Compress Flag", "wcp.flag", FT_UINT8, BASE_HEX, NULL, 0,
666 "Compressed byte flag", HFILL }},
667 { &hf_wcp_comp_marker,
668 { "Compress Marker", "wcp.mark", FT_UINT8, BASE_DEC, NULL, 0,
669 "Compressed marker", HFILL }},
671 { "Source offset", "wcp.off", FT_UINT16, BASE_HEX, NULL, WCP_OFFSET_MASK,
672 "Data source offset", HFILL }},
674 { "Compress Length", "wcp.short_len", FT_UINT8, BASE_HEX, NULL, 0xf0,
675 "Compressed length", HFILL }},
677 { "Compress Length", "wcp.long_len", FT_UINT8, BASE_HEX, NULL, 0,
678 "Compressed length", HFILL }},
680 { "Long Compression", "wcp.long_comp", FT_UINT16, BASE_HEX, NULL, 0,
681 "Long Compression type", HFILL }},
683 { "Short Compression", "wcp.short_comp", FT_UINT8, BASE_HEX, NULL, 0,
684 "Short Compression type", HFILL }},
689 static gint *ett[] = {
694 proto_wcp = proto_register_protocol ("Wellfleet Compression", "WCP", "wcp");
695 proto_register_field_array (proto_wcp, hf, array_length(hf));
696 proto_register_subtree_array(ett, array_length(ett));
701 proto_reg_handoff_wcp(void) {
702 dissector_handle_t wcp_handle;
705 * Get handle for the Frame Relay (uncompressed) dissector.
707 fr_uncompressed_handle = find_dissector("fr_uncompressed");
709 wcp_handle = create_dissector_handle(dissect_wcp, proto_wcp);
710 dissector_add("fr.ietf", NLPID_COMPRESSED, wcp_handle);
711 dissector_add("ethertype", ETHERTYPE_WCP, wcp_handle);