Move dissectors to epan/dissectors directory.

Also move ncp222.py, x11-fields, process-x11-fields.pl,
make-reg-dotc, and make-reg-dotc.py.

Adjust #include lines in files that include packet-*.h
files.

svn path=/trunk/; revision=11410

1 files changed, 900 insertions, 0 deletions

diff --git a/epan/dissectors/packet-vj.c b/epan/dissectors/packet-vj.c
new file mode 100644
index 0000000000..30bbe0cbca
--- /dev/null
+++ b/epan/dissectors/packet-vj.c
@@ -0,0 +1,900 @@
+/* packet-vj.c
+ * Routines for Van Jacobson header decompression.
+ *
+ * $Id$
+ *
+ * Ethereal - Network traffic analyzer
+ * By Gerald Combs <gerald@ethereal.com>
+ *
+ * This file created by Irfan Khan <ikhan@qualcomm.com>
+ * Copyright (c) 2001  by QUALCOMM, Incorporated.
+ * All Rights reserved.
+ *
+ * Routines to compress and uncompress TCP packets (for transmission
+ * over low speed serial lines).
+ *
+ * Copyright (c) 1989 Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that the above copyright notice and this paragraph are
+ * duplicated in all such forms and that any documentation,
+ * advertising materials, and other materials related to such
+ * distribution and use acknowledge that the software was developed
+ * by the University of California, Berkeley.  The name of the
+ * University may not be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ *      Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
+ *      - Initial distribution.
+ *
+ *
+ * modified for KA9Q Internet Software Package by
+ * Katie Stevens (dkstevens@ucdavis.edu)
+ * University of California, Davis
+ * Computing Services
+ *      - 01-31-90      initial adaptation (from 1.19)
+ *      PPP.05  02-15-90 [ks]
+ *      PPP.08  05-02-90 [ks]   use PPP protocol field to signal compression
+ *      PPP.15  09-90    [ks]   improve mbuf handling
+ *      PPP.16  11-02    [karn] substantially rewritten to use NOS facilities
+ *
+ *      - Feb 1991      Bill_Simpson@um.cc.umich.edu
+ *                      variable number of conversation slots
+ *                      allow zero or one slots
+ *                      separate routines
+ *                      status display
+ *      - Jul 1994      Dmitry Gorodchanin
+ *                      Fixes for memory leaks.
+ *      - Oct 1994      Dmitry Gorodchanin
+ *                      Modularization.
+ *      - Jan 1995      Bjorn Ekwall
+ *                      Use ip_fast_csum from ip.h
+ *      - July 1995     Christos A. Polyzols
+ *                      Spotted bug in tcp option checking
+ *      - Sep 2001      Irfan Khan
+ *                      Rewrite to make the code work for ethereal.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <glib.h>
+#include <string.h>
+#include <epan/packet.h>
+#include "prefs.h"
+#include "packet-ppp.h"
+#include "ppptypes.h"
+#include "ipproto.h"
+#include "in_cksum.h"
+
+/* Define relevant IP/TCP parameters */
+#define IP_FIELD_TOT_LEN      2 /* Total length field in IP hdr           */
+#define IP_FIELD_PROTOCOL     9 /* Protocol field byte in IP hdr          */
+#define IP_ADDR_SIZE          4 /* Size in bytes of IPv4 address          */
+#define IP_FIELD_SRC         12 /* Byte 12 in IP hdr - src address        */
+#define IP_FIELD_DST         16 /* Byte 16 in IP hdr - dst address        */
+#define IP_HDR_LEN           20 /* Minimum IP header length               */
+#define IP_HDR_LEN_MASK    0x0f /* Mask for header length field           */
+#define IP_MAX_OPT_LEN       44 /* Max length of IP options               */
+#define TCP_FIELD_HDR_LEN    12 /* Data offset field in TCP hdr           */
+#define TCP_HDR_LEN          20 /* Minimum TCP header length              */
+#define TCP_MAX_OPT_LEN      44 /* Max length of TCP options              */
+#define TCP_SIMUL_CONV_MAX  256 /* Max number of simul. TCP conversations */
+#define TCP_PUSH_BIT       0x08 /* TCP push bit                           */
+#define TCP_URG_BIT        0x20 /* TCP urgent bit                         */
+
+/* Bits in first octet of compressed packet */
+/* flag bits for what changed in a packet */
+#define NEW_C           0x40 /* Connection number changed               */
+#define NEW_I           0x20 /* IP sequence number change by value != 1 */
+#define CHANGE_PUSH_BIT 0x10 /* TCP push bit set                        */
+#define NEW_S           0x08 /* Sequence number changed                 */
+#define NEW_A           0x04 /* Ack sequence number changed             */
+#define NEW_W           0x02 /* Window changed                          */
+#define NEW_U           0x01 /* Urgent pointer present                  */
+
+/* reserved, special-case values of above */
+#define SPECIAL_I     (NEW_S|NEW_W|NEW_U)    /* echoed interactive traffic */
+#define SPECIAL_D     (NEW_S|NEW_A|NEW_W|NEW_U)/* unidirectional data */
+#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
+
+/* Function return values */
+#define VJ_OK           0
+#define VJ_ERROR       -1
+
+/* Define for 0 */
+#define ZERO            0
+
+/* VJ Mem Chunk defines */
+#define VJ_DATA_SIZE  128 /* Max IP hdr(64)+Max TCP hdr(64) */
+#define VJ_ATOM_COUNT 250 /* Number of Atoms per block      */
+
+/* IP and TCP header types */
+typedef struct {
+  guint8  ihl_version;
+  guint8  tos;
+  guint16 tot_len;
+  guint16 id;
+  guint16 frag_off;
+  guint8  ttl;
+  guint8  proto;
+  guint16 cksum;
+  guint32 src;
+  guint32 dst;
+} iphdr_type;
+
+typedef struct {
+  guint16 srcport;
+  guint16 dstport;
+  guint32 seq;
+  guint32 ack_seq;
+  guint8  off_x2;
+  guint8  flags;
+  guint16 window;
+  guint16 cksum;
+  guint16 urg_ptr;
+} tcphdr_type;
+
+#define TCP_OFFSET(th)  (((th)->off_x2 & 0xf0) >> 4)
+
+/* State per active tcp conversation */
+typedef struct cstate {
+  iphdr_type cs_ip;
+  tcphdr_type cs_tcp;
+  guint8 cs_ipopt[IP_MAX_OPT_LEN];
+  guint8 cs_tcpopt[TCP_MAX_OPT_LEN];
+  guint32 flags;
+#define SLF_TOSS  0x00000001    /* tossing rcvd frames until id received */
+} cstate;
+
+/* All the state data for one serial line */
+typedef struct {
+  cstate rstate[TCP_SIMUL_CONV_MAX]; /* receive connection states (array) */
+  guint8 recv_current;               /* most recent rcvd id */
+} slcompress;
+
+/* Initialize the protocol and registered fields */
+static int proto_vj = -1;
+
+static int hf_vj_change_mask = -1;
+static int hf_vj_change_mask_c = -1;
+static int hf_vj_change_mask_i = -1;
+static int hf_vj_change_mask_p = -1;
+static int hf_vj_change_mask_s = -1;
+static int hf_vj_change_mask_a = -1;
+static int hf_vj_change_mask_w = -1;
+static int hf_vj_change_mask_u = -1;
+static int hf_vj_connection_number = -1;
+static int hf_vj_tcp_cksum = -1;
+static int hf_vj_urp = -1;
+static int hf_vj_win_delta = -1;
+static int hf_vj_ack_delta = -1;
+static int hf_vj_seq_delta = -1;
+static int hf_vj_ip_id_delta = -1;
+
+static gint ett_vj = -1;
+static gint ett_vj_changes = -1;
+
+/* Protocol handles */
+static dissector_handle_t ip_handle;
+static dissector_handle_t data_handle;
+
+/* State repository (Full Duplex) */
+#define RX_TX_STATE_COUNT 2
+static slcompress *rx_tx_state[RX_TX_STATE_COUNT] = {NULL, NULL};
+
+/* Mem Chunks for storing decompressed headers */
+static GMemChunk *vj_header_memchunk = NULL;
+typedef struct {
+	int	offset;			/* uppermost bit is "can't dissect" flag */
+	guint8	data[VJ_DATA_SIZE];
+} vj_header_t;
+
+/* Function prototypes */
+static int get_unsigned_delta(tvbuff_t *tvb, int *offsetp, int hf,
+                        proto_tree *tree);
+static int get_signed_delta(tvbuff_t *tvb, int *offsetp, int hf,
+                        proto_tree *tree);
+static guint16 ip_csum(const guint8 *ptr, guint32 len);
+static slcompress *slhc_init(void);
+static void vj_init(void);
+static gint vjc_process(tvbuff_t *src_tvb, packet_info *pinfo, proto_tree *tree,
+                      slcompress *comp);
+static gint vjc_tvb_setup(tvbuff_t *src_tvb, tvbuff_t **dst_tvb,
+                          packet_info *pinfo);
+
+/* Dissector for VJ Uncompressed packets */
+static void
+dissect_vjuc(tvbuff_t *tvb, packet_info *pinfo, proto_tree * tree)
+{
+  proto_item *ti;
+  proto_tree *vj_tree     = NULL;
+  slcompress *comp;
+  int         i;
+  gint        conn_index;
+  cstate     *cs          = NULL;
+  guint8      ihl;
+  guint8      thl;
+  guint8     *buffer;
+  tvbuff_t   *next_tvb;
+  gint        isize       = tvb_length(tvb);
+  gint        ipsize;
+
+  if(check_col(pinfo->cinfo, COL_PROTOCOL))
+    col_set_str(pinfo->cinfo, COL_INFO, "PPP VJ");
+
+  if(tree != NULL) {
+    ti = proto_tree_add_protocol_format(tree, proto_vj, tvb, 0, -1,
+                                        "PPP VJ Compression: Uncompressed data");
+    vj_tree = proto_item_add_subtree(ti, ett_vj);
+  }
+
+  if(pinfo->p2p_dir == P2P_DIR_UNKNOWN) {
+    /* Direction of the traffic unknown - can't update state */
+    comp = NULL;
+  } else {
+    /* Get state for that direction */
+    comp = rx_tx_state[pinfo->p2p_dir];
+  }
+
+  /*
+   * Check to make sure we can fetch the connection index.
+   */
+  if(!tvb_bytes_exist(tvb, IP_FIELD_PROTOCOL, 1)) {
+    /*
+     * We don't.  We can't even mark a connection as non-decompressable,
+     * as we don't know which connection this is.  Mark them all as
+     * non-decompressable.
+     */
+    if(check_col(pinfo->cinfo, COL_INFO))
+      col_set_str(pinfo->cinfo, COL_INFO, "VJ uncompressed TCP (not enough data available)");
+    if(tree != NULL)
+      call_dissector(data_handle, tvb, pinfo, tree);
+    if(comp != NULL) {
+      for(i = 0; i < TCP_SIMUL_CONV_MAX; i++)
+        comp->rstate[i].flags |= SLF_TOSS;
+    }
+    return;
+  }
+
+  /* Get connection index */
+  conn_index = tvb_get_guint8(tvb, IP_FIELD_PROTOCOL);
+  if(tree != NULL)
+    proto_tree_add_uint(vj_tree, hf_vj_connection_number, tvb,
+                        IP_FIELD_PROTOCOL, 1, conn_index);
+
+  /*
+   * Update the current connection, and get a pointer to its state.
+   */
+  if(comp != NULL) {
+    comp->recv_current = conn_index;
+    cs = &comp->rstate[conn_index];
+  }
+
+  /* Get the IP header length */
+  ihl = tvb_get_guint8(tvb, 0) & IP_HDR_LEN_MASK;
+  ihl <<= 2;
+
+  /* Check IP header length */
+  if(ihl < IP_HDR_LEN) {
+    if(check_col(pinfo->cinfo, COL_INFO)) {
+      col_add_fstr(pinfo->cinfo, COL_INFO, "VJ uncompressed TCP (IP header length (%u) < %u)",
+                   ihl, IP_HDR_LEN);
+    }
+    if(cs != NULL)
+      cs->flags |= SLF_TOSS;
+    return;
+  }
+
+  /* Make sure we have the full IP header */
+  if(isize < ihl) {
+    if(check_col(pinfo->cinfo, COL_INFO))
+      col_set_str(pinfo->cinfo, COL_INFO, "VJ uncompressed TCP (not enough data available)");
+    if(tree != NULL)
+      call_dissector(data_handle, tvb, pinfo, tree);
+    if(cs != NULL)
+      cs->flags |= SLF_TOSS;
+    return;
+  }
+
+  if(check_col(pinfo->cinfo, COL_INFO))
+    col_set_str(pinfo->cinfo, COL_INFO, "VJ uncompressed TCP");
+
+  /*
+   * Copy packet data to a buffer, and replace the connection index with
+   * the protocol type (which is always TCP), to give the actual IP header.
+   */
+  buffer = tvb_memdup(tvb, 0, isize);
+  buffer[IP_FIELD_PROTOCOL] = IP_PROTO_TCP;
+
+  /* Check IP checksum */
+  if(ip_csum(buffer, ihl) != ZERO) {
+    /*
+     * Checksum invalid - don't update state, and don't decompress
+     * any subsequent compressed packets in this direction.
+     */
+    if(cs != NULL)
+      cs->flags |= SLF_TOSS;
+    cs = NULL;  /* disable state updates */
+  } else {
+    /* Do we have the TCP header length in the tvbuff? */
+    if(!tvb_bytes_exist(tvb, ihl + TCP_FIELD_HDR_LEN, 1)) {
+      /* We don't, so we can't provide enough data for decompression */
+      if(check_col(pinfo->cinfo, COL_INFO))
+        col_set_str(pinfo->cinfo, COL_INFO, "VJ uncompressed TCP (not enough data available)");
+      if(cs != NULL)
+        cs->flags |= SLF_TOSS;
+      cs = NULL;  /* disable state updates */
+    } else {
+      /* Get the TCP header length */
+      thl = tvb_get_guint8(tvb, ihl + TCP_FIELD_HDR_LEN);
+      thl = ((thl & 0xf0) >> 4) * 4;
+
+      /* Check TCP header length */
+      if(thl < TCP_HDR_LEN) {
+        if(check_col(pinfo->cinfo, COL_INFO)) {
+          col_add_fstr(pinfo->cinfo, COL_INFO, "VJ uncompressed TCP (TCP header length (%u) < %u)",
+                       thl, TCP_HDR_LEN);
+        }
+        if(cs != NULL)
+          cs->flags |= SLF_TOSS;
+        cs = NULL;  /* disable state updates */
+      } else {
+        /* Make sure we have the full TCP header */
+        if(isize < thl) {
+          if(check_col(pinfo->cinfo, COL_INFO))
+            col_set_str(pinfo->cinfo, COL_INFO, "VJ uncompressed TCP (not enough data available)");
+          if(cs != NULL)
+            cs->flags |= SLF_TOSS;
+          cs = NULL;  /* disable state updates */
+        }
+      }
+    }
+  }
+
+  /*
+   * If packet seen for first time, update state if we have state and can
+   * update it.
+   */
+  if(!pinfo->fd->flags.visited) {
+    if(cs != NULL) {
+      cs->flags &= ~SLF_TOSS;
+      memcpy(&cs->cs_ip, &buffer[0], IP_HDR_LEN);
+      memcpy(&cs->cs_tcp, &buffer[ihl], TCP_HDR_LEN);
+      if(ihl > IP_HDR_LEN)
+        memcpy(cs->cs_ipopt, &buffer[sizeof(iphdr_type)], ihl - IP_HDR_LEN);
+      if(TCP_OFFSET(&(cs->cs_tcp)) > 5)
+        memcpy(cs->cs_tcpopt, &buffer[ihl + sizeof(tcphdr_type)],
+                   (TCP_OFFSET(&(cs->cs_tcp)) - 5) * 4);
+    }
+  }
+
+  /*
+   * Set up tvbuff containing packet with protocol type.
+   * Neither header checksum is recalculated.
+   *
+   * Use the length field from the IP header as the reported length;
+   * use the minimum of that and the number of bytes we got from
+   * the tvbuff as the actual length, just in case the tvbuff we were
+   * handed includes part or all of the FCS (because the FCS preference
+   * for the PPP dissector doesn't match the FCS size in this session).
+   */
+  ipsize = pntohs(&buffer[IP_FIELD_TOT_LEN]);
+  if (ipsize < isize)
+    isize = ipsize;
+  next_tvb = tvb_new_real_data(buffer, isize, ipsize);
+  tvb_set_child_real_data_tvbuff(tvb, next_tvb);
+  add_new_data_source(pinfo, next_tvb, "VJ Uncompressed");
+
+  /*
+   * Call IP dissector.
+   */
+  call_dissector(ip_handle, next_tvb, pinfo, tree);
+}
+
+/* Dissector for VJ Compressed packets */
+static void
+dissect_vjc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+  proto_item *ti;
+  proto_tree *vj_tree     = NULL;
+  tvbuff_t   *next_tvb = NULL;
+  slcompress *comp     = NULL;
+  gint        err      = VJ_ERROR;
+
+  if(check_col(pinfo->cinfo, COL_PROTOCOL))
+    col_set_str(pinfo->cinfo, COL_INFO, "PPP VJ");
+
+  if(tree != NULL) {
+    ti = proto_tree_add_protocol_format(tree, proto_vj, tvb, 0, -1,
+                                        "PPP VJ Compression: Compressed data");
+    vj_tree = proto_item_add_subtree(ti, ett_vj);
+  }
+
+  if(!ppp_vj_decomp || pinfo->p2p_dir == P2P_DIR_UNKNOWN) {
+    /*
+     * VJ decompression turned off, so we shouldn't decompress, or
+     * direction of the traffic unknown, so we can't decompress.
+     */
+    comp = NULL;
+  } else {
+    /* Get state for that direction */
+    comp = rx_tx_state[pinfo->p2p_dir];
+  }
+
+  /* Process the compressed data header */
+  if(vjc_process(tvb, pinfo, vj_tree, comp) == VJ_ERROR)
+    return;
+
+  /* Decompression possible - set up tvb containing decompressed packet */
+  err = vjc_tvb_setup(tvb, &next_tvb, pinfo);
+  if(err == VJ_ERROR) {
+    if(tree != NULL)
+      call_dissector(data_handle, tvb, pinfo, vj_tree);
+    return;
+  }
+
+  /* No errors, so call IP dissector */
+  call_dissector(ip_handle, next_tvb, pinfo, tree);
+}
+
+/* Registration functions for dissectors */
+void
+proto_register_vj(void)
+{
+  static hf_register_info hf[] = {
+    { &hf_vj_change_mask,
+      { "Change mask",	"vj.change_mask",	FT_UINT8, BASE_HEX,
+        NULL, 0x0, "", HFILL }},
+    { &hf_vj_change_mask_c,
+      { "Connection changed",		"vj.change_mask_c",	FT_BOOLEAN, 8,
+        NULL, NEW_C, "Connection number changed", HFILL }},
+    { &hf_vj_change_mask_i,
+      { "IP ID change != 1",		"vj.change_mask_i",	FT_BOOLEAN, 8,
+        NULL, NEW_I, "IP ID changed by a value other than 1", HFILL }},
+    { &hf_vj_change_mask_p,
+      { "Push bit set",			"vj.change_mask_p",	FT_BOOLEAN, 8,
+        NULL, CHANGE_PUSH_BIT, "TCP PSH flag set", HFILL }},
+    { &hf_vj_change_mask_s,
+      { "Sequence number changed",	"vj.change_mask_s",	FT_BOOLEAN, 8,
+        NULL, NEW_S, "Sequence number changed", HFILL }},
+    { &hf_vj_change_mask_a,
+      { "Ack number changed",		"vj.change_mask_a",	FT_BOOLEAN, 8,
+        NULL, NEW_A, "Acknowledgement sequence number changed", HFILL }},
+    { &hf_vj_change_mask_w,
+      { "Window changed",		"vj.change_mask_w",	FT_BOOLEAN, 8,
+        NULL, NEW_W, "TCP window changed", HFILL }},
+    { &hf_vj_change_mask_u,
+      { "Urgent pointer set",		"vj.change_mask_u",	FT_BOOLEAN, 8,
+        NULL, NEW_U, "Urgent pointer set", HFILL }},
+    { &hf_vj_connection_number,
+      { "Connection number",	"vj.connection_number",	FT_UINT8, BASE_DEC,
+        NULL, 0x0, "Connection number", HFILL }},
+    { &hf_vj_tcp_cksum,
+      { "TCP checksum",			"vj.tcp_cksum",	FT_UINT16, BASE_HEX,
+        NULL, 0x0, "TCP checksum", HFILL }},
+    { &hf_vj_urp,
+      { "Urgent pointer",		"vj.urp",	FT_UINT16, BASE_DEC,
+        NULL, 0x0, "Urgent pointer", HFILL }},
+    { &hf_vj_win_delta,
+      { "Window delta",			"vj.win_delta",	FT_INT16, BASE_DEC,
+        NULL, 0x0, "Delta for window", HFILL }},
+    { &hf_vj_ack_delta,
+      { "Ack delta",			"vj.ack_delta",	FT_UINT16, BASE_DEC,
+        NULL, 0x0, "Delta for acknowledgment sequence number", HFILL }},
+    { &hf_vj_seq_delta,
+      { "Sequence delta",		"vj.seq_delta",	FT_UINT16, BASE_DEC,
+        NULL, 0x0, "Delta for sequence number", HFILL }},
+    { &hf_vj_ip_id_delta,
+      { "IP ID delta",			"vj.ip_id_delta",	FT_UINT16, BASE_DEC,
+        NULL, 0x0, "Delta for IP ID", HFILL }},
+  };
+  static gint *ett[] = {
+    &ett_vj,
+    &ett_vj_changes,
+  };
+
+  proto_vj = proto_register_protocol("PPP VJ Compression", "PPP VJ", "vj");
+  proto_register_field_array(proto_vj, hf, array_length(hf));
+  proto_register_subtree_array(ett, array_length(ett));
+  register_init_routine(&vj_init);
+}
+
+void
+proto_reg_handoff_vj(void)
+{
+  dissector_handle_t vjc_handle;
+  dissector_handle_t vjuc_handle;
+
+  vjc_handle = create_dissector_handle(dissect_vjc, proto_vj);
+  dissector_add("ppp.protocol", PPP_VJC_COMP, vjc_handle);
+
+  vjuc_handle = create_dissector_handle(dissect_vjuc, proto_vj);
+  dissector_add("ppp.protocol", PPP_VJC_UNCOMP, vjuc_handle);
+
+  ip_handle = find_dissector("ip");
+  data_handle = find_dissector("data");
+}
+
+/* Initialization function */
+static void
+vj_init(void)
+{
+  gint i           = ZERO;
+  slcompress *pslc = NULL;
+
+  if(vj_header_memchunk != NULL)
+    g_mem_chunk_destroy(vj_header_memchunk);
+  vj_header_memchunk = g_mem_chunk_new("vj header store", sizeof (vj_header_t),
+                                       sizeof (vj_header_t) * VJ_ATOM_COUNT,
+                                       G_ALLOC_ONLY);
+  for(i = 0; i < RX_TX_STATE_COUNT; i++) {
+    if((pslc = rx_tx_state[i]) != NULL)
+      g_free(pslc);
+    rx_tx_state[i] = slhc_init();
+  }
+  return;
+}
+
+/* Initialization routine for VJ decompression */
+static slcompress *
+slhc_init(void)
+{
+  slcompress *comp = g_malloc(sizeof(slcompress));
+  int         i;
+
+  memset(comp, ZERO, sizeof(slcompress));
+
+  /*
+   * Initialize the state; there is no current connection, and
+   * we have no header data for any of the connections, as we
+   * haven't yet seen an uncompressed frame.
+   */
+  comp->recv_current = TCP_SIMUL_CONV_MAX - 1;
+  for (i = 0; i < TCP_SIMUL_CONV_MAX; i++)
+    comp->rstate[i].flags |= SLF_TOSS;
+  return comp;
+}
+
+/* Setup the decompressed packet tvb for VJ compressed packets */
+static gint
+vjc_tvb_setup(tvbuff_t *src_tvb,
+              tvbuff_t **dst_tvb,
+              packet_info *pinfo)
+{
+  vj_header_t *hdr_buf;
+  guint8       offset;
+  guint8      *data_ptr;
+  iphdr_type  *ip;
+  tcphdr_type *thp;
+  gint         hdr_len;
+  gint         buf_len;
+  guint8      *pbuf;
+
+  g_assert(src_tvb);
+
+  /* Get decompressed header stored in fd protocol area */
+  hdr_buf = p_get_proto_data(pinfo->fd, proto_vj);
+  if(hdr_buf == NULL) {
+    if(check_col(pinfo->cinfo, COL_INFO))
+      col_set_str(pinfo->cinfo, COL_INFO, "VJ compressed TCP (previous data bad or missing)");
+    return VJ_ERROR;
+  }
+
+  if(check_col(pinfo->cinfo, COL_INFO))
+    col_set_str(pinfo->cinfo, COL_INFO, "VJ compressed TCP");
+
+  /* Get the data offset in the tvbuff */
+  offset  = hdr_buf->offset;
+
+  /* Copy header and form tvb */
+  data_ptr = hdr_buf->data;
+  ip = (iphdr_type *)data_ptr;
+  hdr_len  = lo_nibble(ip->ihl_version) * 4;
+  thp = (tcphdr_type *)(data_ptr + hdr_len);
+  hdr_len += TCP_OFFSET(thp) * 4;
+  buf_len  = tvb_length(src_tvb) + hdr_len - offset;
+  pbuf     = g_malloc(buf_len);
+  memcpy(pbuf, data_ptr, hdr_len);
+  tvb_memcpy(src_tvb, pbuf + hdr_len, offset, buf_len - hdr_len);
+  *dst_tvb = tvb_new_real_data(pbuf, buf_len, g_ntohs(ip->tot_len));
+  tvb_set_child_real_data_tvbuff(src_tvb, *dst_tvb);
+  add_new_data_source(pinfo, *dst_tvb, "VJ Decompressed");
+  return VJ_OK;
+}
+
+/*
+ * For VJ compressed packet:
+ *
+ *	check if it is malformed;
+ *	dissect the relevant fields;
+ *	update the decompressor state on the first pass.
+ */
+static gint
+vjc_process(tvbuff_t *src_tvb, packet_info *pinfo, proto_tree *tree,
+            slcompress *comp)
+{
+  int            offset     = ZERO;
+  int            i;
+  gint           changes;
+  proto_item    *ti;
+  proto_tree    *changes_tree;
+  guint8         conn_index;
+  cstate        *cs         = NULL;
+  iphdr_type    *ip         = NULL;
+  tcphdr_type   *thp        = NULL;
+  guint16        tcp_cksum;
+  gint           hdrlen     = ZERO;
+  guint16        word;
+  int            delta;
+  gint           len;
+  vj_header_t   *buf_hdr;
+  guint8        *data_ptr;
+
+  if(tvb_length(src_tvb) < 3){
+    /*
+     * We don't even have enough data for the change byte, so we can't
+     * determine which connection this is; mark all connections as
+     * non-decompressible.
+     */
+    if(check_col(pinfo->cinfo, COL_INFO))
+      col_set_str(pinfo->cinfo, COL_INFO, "VJ compressed TCP (not enough data available)");
+    if(tree != NULL)
+      call_dissector(data_handle, src_tvb, pinfo, tree);
+    if(comp != NULL) {
+      for(i = 0; i < TCP_SIMUL_CONV_MAX; i++)
+        comp->rstate[i].flags |= SLF_TOSS;
+    }
+    return VJ_ERROR;
+  }
+
+  /* Read the change byte */
+  changes = tvb_get_guint8(src_tvb, offset);
+  if(tree != NULL) {
+    switch (changes & SPECIALS_MASK) {
+
+    case SPECIAL_I:
+      ti = proto_tree_add_uint_format(tree, hf_vj_change_mask, src_tvb,
+                                      offset, 1, changes,
+                                      "Change mask: 0x%02x (echoed interactive traffic)",
+                                      changes);
+      break;
+
+    case SPECIAL_D:
+      ti = proto_tree_add_uint_format(tree, hf_vj_change_mask, src_tvb,
+                                      offset, 1, changes,
+                                      "Change mask: 0x%02x (unidirectional data)",
+                                      changes);
+      break;
+
+    default:
+      /*
+       * XXX - summarize bits?
+       */
+      ti = proto_tree_add_uint_format(tree, hf_vj_change_mask, src_tvb,
+                                      offset, 1, changes,
+                                      "Change mask: 0x%02x", changes);
+      break;
+    }
+    changes_tree = proto_item_add_subtree(ti, ett_vj_changes);
+    proto_tree_add_boolean(changes_tree, hf_vj_change_mask_c, src_tvb,
+                           offset, 1, changes);
+    proto_tree_add_boolean(changes_tree, hf_vj_change_mask_i, src_tvb,
+                           offset, 1, changes);
+    proto_tree_add_boolean(changes_tree, hf_vj_change_mask_p, src_tvb,
+                           offset, 1, changes);
+    proto_tree_add_boolean(changes_tree, hf_vj_change_mask_s, src_tvb,
+                           offset, 1, changes);
+    proto_tree_add_boolean(changes_tree, hf_vj_change_mask_a, src_tvb,
+                           offset, 1, changes);
+    proto_tree_add_boolean(changes_tree, hf_vj_change_mask_w, src_tvb,
+                           offset, 1, changes);
+    proto_tree_add_boolean(changes_tree, hf_vj_change_mask_u, src_tvb,
+                           offset, 1, changes);
+  }
+  offset++;
+
+  if(changes & NEW_C){    /* Read conn index */
+    conn_index = tvb_get_guint8(src_tvb, offset);
+    if(tree != NULL)
+      proto_tree_add_uint(tree, hf_vj_connection_number, src_tvb, offset, 1,
+                          conn_index);
+    offset++;
+    if(comp != NULL)
+      comp->recv_current = conn_index;
+  }
+
+  if(!pinfo->fd->flags.visited) {
+    /*
+     * This is the first time this frame has been seen, so we need
+     * state information to decompress it.  If that information isn't
+     * available, don't use the state information, and don't update it,
+     * either.
+     */
+    if(comp != NULL && !(comp->rstate[comp->recv_current].flags & SLF_TOSS)) {
+      cs = &comp->rstate[comp->recv_current];
+      thp = &cs->cs_tcp;
+      ip = &cs->cs_ip;
+    }
+  }
+
+  /* Build TCP and IP headers */
+  tcp_cksum = tvb_get_ntohs(src_tvb, offset);
+  if(tree != NULL)
+    proto_tree_add_uint(tree, hf_vj_tcp_cksum, src_tvb, offset, 2, tcp_cksum);
+  if(cs != NULL) {
+    hdrlen = lo_nibble(ip->ihl_version) * 4 + TCP_OFFSET(thp) * 4;
+    thp->cksum = g_htons(tcp_cksum);
+  }
+  offset += 2;
+  if(cs != NULL) {
+    if(changes & CHANGE_PUSH_BIT)
+      thp->flags |= TCP_PUSH_BIT;
+    else
+      thp->flags &= ~TCP_PUSH_BIT;
+  }
+
+  /* Deal with special cases and normal deltas */
+  switch(changes & SPECIALS_MASK){
+    case SPECIAL_I:                   /* Echoed terminal traffic */
+      if(cs != NULL) {
+        word = g_ntohs(ip->tot_len) - hdrlen;
+        thp->ack_seq = g_htonl(g_ntohl(thp->ack_seq) + word);
+        thp->seq = g_htonl(g_ntohl(thp->seq) + word);
+      }
+      break;
+    case SPECIAL_D:                   /* Unidirectional data */
+      if(cs != NULL)
+        thp->seq = g_htonl(g_ntohl(thp->seq) + g_ntohs(ip->tot_len) - hdrlen);
+      break;
+    default:
+      if(changes & NEW_U){
+        delta = get_unsigned_delta(src_tvb, &offset, hf_vj_urp, tree);
+        if(cs != NULL) {
+          thp->urg_ptr = delta;
+          thp->flags |= TCP_URG_BIT;
+        }
+      } else {
+        if(cs != NULL)
+          thp->flags &= ~TCP_URG_BIT;
+      }
+      if(changes & NEW_W) {
+        delta = get_signed_delta(src_tvb, &offset, hf_vj_win_delta, tree);
+        if(cs != NULL)
+          thp->window = g_htons(g_ntohs(thp->window) + delta);
+      }
+      if(changes & NEW_A) {
+        delta = get_unsigned_delta(src_tvb, &offset, hf_vj_ack_delta, tree);
+        if(cs != NULL)
+          thp->ack_seq = g_htonl(g_ntohl(thp->ack_seq) + delta);
+      }
+      if(changes & NEW_S) {
+      	delta = get_unsigned_delta(src_tvb, &offset, hf_vj_seq_delta, tree);
+        if(cs != NULL)
+          thp->seq = g_htonl(g_ntohl(thp->seq) + delta);
+      }
+      break;
+  }
+  if(changes & NEW_I)
+    delta = get_unsigned_delta(src_tvb, &offset, hf_vj_ip_id_delta, tree);
+  else
+    delta = 1;
+  if(cs != NULL)
+    ip->id = g_htons(g_ntohs(ip->id) + delta);
+
+  /* Compute IP packet length and the buffer length needed */
+  len = tvb_reported_length_remaining(src_tvb, offset);
+  if(len < ZERO) {
+    /*
+     * This shouldn't happen, as we *were* able to fetch stuff right before
+     * offset.
+     */
+    if(check_col(pinfo->cinfo, COL_INFO))
+      col_set_str(pinfo->cinfo, COL_INFO, "VJ compressed TCP (not enough data available)");
+    if(cs != NULL)
+      cs->flags |= SLF_TOSS;
+    return VJ_ERROR;
+  }
+
+  /* Show the TCP payload */
+  if(tree != NULL && tvb_offset_exists(src_tvb, offset))
+    proto_tree_add_text(tree, src_tvb, offset, -1, "TCP payload");
+
+  /* Nothing more to do if we don't have any compression state */
+  if(comp == NULL) {
+    /* Direction of the traffic unknown - can't decompress */
+    if(check_col(pinfo->cinfo, COL_INFO))
+      col_set_str(pinfo->cinfo, COL_INFO, "VJ compressed TCP (direction unknown)");
+    return VJ_ERROR;
+  }
+
+  if(cs != NULL) {
+    len += hdrlen;
+    ip->tot_len = g_htons(len);
+    /* Compute IP check sum */
+    ip->cksum = ZERO;
+    ip->cksum = ip_csum((guint8 *)ip, lo_nibble(ip->ihl_version) * 4);
+
+    /* Store the reconstructed header in frame data area */
+    buf_hdr = g_mem_chunk_alloc(vj_header_memchunk);
+    buf_hdr->offset = offset;  /* Offset in tvbuff is also stored */
+    data_ptr = buf_hdr->data;
+    memcpy(data_ptr, ip, IP_HDR_LEN);
+    data_ptr += IP_HDR_LEN;
+    if(lo_nibble(ip->ihl_version) > 5) {
+      memcpy(data_ptr, cs->cs_ipopt, (lo_nibble(ip->ihl_version) - 5) * 4);
+      data_ptr += (lo_nibble(ip->ihl_version) - 5) * 4;
+    }
+    memcpy(data_ptr, thp, TCP_HDR_LEN);
+    data_ptr += TCP_HDR_LEN;
+    if(TCP_OFFSET(thp) > 5)
+      memcpy(data_ptr, cs->cs_tcpopt, (TCP_OFFSET(thp) - 5) * 4);
+    p_add_proto_data(pinfo->fd, proto_vj, buf_hdr);
+  }
+
+  return VJ_OK;
+}
+
+/*
+ * Get an unsigned delta for a field, and put it into the protocol tree if
+ * we're building a protocol tree.
+ */
+static int
+get_unsigned_delta(tvbuff_t *tvb, int *offsetp, int hf, proto_tree *tree)
+{
+  int offset = *offsetp;
+  int len;
+  guint16 del;
+
+  len = 1;
+  del = tvb_get_guint8(tvb, offset++);
+  if(del == ZERO){
+    del = tvb_get_ntohs(tvb, offset);
+    offset += 2;
+    len += 2;
+  }
+  if(tree != NULL)
+    proto_tree_add_uint(tree, hf, tvb, *offsetp, len, del);
+  *offsetp = offset;
+  return del;
+}
+
+/*
+ * Get a signed delta for a field, and put it into the protocol tree if
+ * we're building a protocol tree.
+ */
+static int
+get_signed_delta(tvbuff_t *tvb, int *offsetp, int hf, proto_tree *tree)
+{
+  int offset = *offsetp;
+  int len;
+  gint16 del;
+
+  len = 1;
+  del = tvb_get_guint8(tvb, offset++);
+  if(del == ZERO){
+    del = tvb_get_ntohs(tvb, offset);
+    offset += 2;
+    len += 2;
+  }
+  if(tree != NULL)
+    proto_tree_add_int(tree, hf, tvb, *offsetp, len, del);
+  *offsetp = offset;
+  return del;
+}
+
+/* Wrapper for in_cksum function */
+static guint16
+ip_csum(const guint8 * ptr, guint32 len)
+{
+  vec_t cksum_vec[1];
+
+  cksum_vec[0].ptr = ptr;
+  cksum_vec[0].len = len;
+  return in_cksum(&cksum_vec[0], 1);
+}