/* packet-fddi.c
 * Routines for FDDI packet disassembly
 *
 * ANSI Standard X3T9.5/88-139, Rev 4.0
 *
 * ISO Standards 9314-N (N = 1 for PHY, N = 2 for MAC, N = 6 for SMT, etc.)
 *
 * Laurent Deniel <laurent.deniel@free.fr>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#include <epan/packet.h>
#include <wsutil/bitswap.h>
#include <epan/prefs.h>
#include <epan/conversation_table.h>
#include <epan/capture_dissectors.h>
#include "packet-llc.h"
#include "packet-sflow.h"

#include <epan/addr_resolv.h>

void proto_register_fddi(void);
void proto_reg_handoff_fddi(void);

static int proto_fddi = -1;
static int hf_fddi_fc = -1;
static int hf_fddi_fc_clf = -1;
static int hf_fddi_fc_prio = -1;
static int hf_fddi_fc_smt_subtype = -1;
static int hf_fddi_fc_mac_subtype = -1;
static int hf_fddi_dst = -1;
static int hf_fddi_src = -1;
static int hf_fddi_addr = -1;

static gint ett_fddi = -1;
static gint ett_fddi_fc = -1;

static int fddi_tap = -1;

static dissector_handle_t fddi_handle, fddi_bitswapped_handle;

static capture_dissector_handle_t llc_cap_handle;

static gboolean fddi_padding = FALSE;

#define FDDI_PADDING            ((fddi_padding) ? 3 : 0)

/* FDDI Frame Control values */

#define FDDI_FC_VOID            0x00            /* Void frame */
#define FDDI_FC_NRT             0x80            /* Nonrestricted token */
#define FDDI_FC_RT              0xc0            /* Restricted token */
#define FDDI_FC_MAC             0xc0            /* MAC frame */
#define FDDI_FC_SMT             0x40            /* SMT frame */
#define FDDI_FC_SMT_INFO        0x41            /* SMT Info */
#define FDDI_FC_SMT_NSA         0x4F            /* SMT Next station adrs */
#define FDDI_FC_SMT_MIN         FDDI_FC_SMT_INFO
#define FDDI_FC_SMT_MAX         FDDI_FC_SMT_NSA
#define FDDI_FC_MAC_MIN         0xc1
#define FDDI_FC_MAC_BEACON      0xc2            /* MAC Beacon frame */
#define FDDI_FC_MAC_CLAIM       0xc3            /* MAC Claim frame */
#define FDDI_FC_MAC_MAX         0xcf
#define FDDI_FC_LLC_ASYNC       0x50            /* Async. LLC frame */
#define FDDI_FC_LLC_ASYNC_MIN   FDDI_FC_LLC_ASYNC
#define FDDI_FC_LLC_ASYNC_DEF   0x54
#define FDDI_FC_LLC_ASYNC_MAX   0x5f
#define FDDI_FC_LLC_SYNC        0xd0            /* Sync. LLC frame */
#define FDDI_FC_LLC_SYNC_MIN    FDDI_FC_LLC_SYNC
#define FDDI_FC_LLC_SYNC_MAX    0xd7
#define FDDI_FC_IMP_ASYNC       0x60            /* Implementor Async. */
#define FDDI_FC_IMP_ASYNC_MIN   FDDI_FC_IMP_ASYNC
#define FDDI_FC_IMP_ASYNC_MAX   0x6f
#define FDDI_FC_IMP_SYNC        0xe0            /* Implementor Synch. */

#define FDDI_FC_CLFF            0xF0            /* Class/Length/Format bits */
#define FDDI_FC_ZZZZ            0x0F            /* Control bits */

/*
 * Async frame ZZZZ bits:
 */
#define FDDI_FC_ASYNC_R         0x08            /* Reserved */
#define FDDI_FC_ASYNC_PRI       0x07            /* Priority */

#define CLFF_BITS(fc)   (((fc) & FDDI_FC_CLFF) >> 4)
#define ZZZZ_BITS(fc)   ((fc) & FDDI_FC_ZZZZ)

static const value_string clf_vals[] = {
  { CLFF_BITS(FDDI_FC_VOID),      "Void" },
  { CLFF_BITS(FDDI_FC_SMT),       "SMT" },
  { CLFF_BITS(FDDI_FC_LLC_ASYNC), "Async LLC" },
  { CLFF_BITS(FDDI_FC_IMP_ASYNC), "Implementor Async" },
  { CLFF_BITS(FDDI_FC_NRT),       "Nonrestricted Token" },
  { CLFF_BITS(FDDI_FC_MAC),       "MAC" },
  { CLFF_BITS(FDDI_FC_LLC_SYNC),  "Sync LLC" },
  { CLFF_BITS(FDDI_FC_IMP_SYNC),  "Implementor Sync" },
  { 0,                            NULL }
};

static const value_string smt_subtype_vals[] = {
  { ZZZZ_BITS(FDDI_FC_SMT_INFO), "Info" },
  { ZZZZ_BITS(FDDI_FC_SMT_NSA),  "Next Station Address" },
  { 0,                           NULL }
};

static const value_string mac_subtype_vals[] = {
  { ZZZZ_BITS(FDDI_FC_MAC_BEACON), "Beacon" },
  { ZZZZ_BITS(FDDI_FC_MAC_CLAIM),  "Claim" },
  { 0,                             NULL }
};

typedef struct _fddi_hdr {
  guint8  fc;
  address dst;
  address src;
} fddi_hdr;

#define FDDI_HEADER_SIZE       13

/* field positions */

#define FDDI_P_FC               0
#define FDDI_P_DHOST            1
#define FDDI_P_SHOST            7

static dissector_handle_t llc_handle;

static void
swap_mac_addr(guint8 *swapped_addr, tvbuff_t *tvb, gint offset)
{
  tvb_memcpy(tvb, swapped_addr, offset, 6);
  bitswap_buf_inplace(swapped_addr, 6);
}

static const char* fddi_conv_get_filter_type(conv_item_t* conv, conv_filter_type_e filter)
{
  if ((filter == CONV_FT_SRC_ADDRESS) && (conv->src_address.type == AT_ETHER))
    return "fddi.src";

  if ((filter == CONV_FT_DST_ADDRESS) && (conv->dst_address.type == AT_ETHER))
    return "fddi.dst";

  if ((filter == CONV_FT_ANY_ADDRESS) && (conv->src_address.type == AT_ETHER))
    return "fddi.addr";

  return CONV_FILTER_INVALID;
}

static ct_dissector_info_t fddi_ct_dissector_info = {&fddi_conv_get_filter_type};

static tap_packet_status
fddi_conversation_packet(void *pct, packet_info *pinfo, epan_dissect_t *edt _U_, const void *vip)
{
  conv_hash_t *hash = (conv_hash_t*) pct;
  const fddi_hdr *ehdr=(const fddi_hdr *)vip;

  add_conversation_table_data(hash, &ehdr->src, &ehdr->dst, 0, 0, 1, pinfo->fd->pkt_len, &pinfo->rel_ts, &pinfo->abs_ts, &fddi_ct_dissector_info, ENDPOINT_NONE);

  return TAP_PACKET_REDRAW;
}

static const char* fddi_host_get_filter_type(hostlist_talker_t* host, conv_filter_type_e filter)
{
  if ((filter == CONV_FT_ANY_ADDRESS) && (host->myaddress.type == AT_ETHER))
    return "fddi.addr";

  return CONV_FILTER_INVALID;
}

static hostlist_dissector_info_t fddi_host_dissector_info = {&fddi_host_get_filter_type};

static tap_packet_status
fddi_hostlist_packet(void *pit, packet_info *pinfo, epan_dissect_t *edt _U_, const void *vip)
{
  conv_hash_t *hash = (conv_hash_t*) pit;
  const fddi_hdr *ehdr=(const fddi_hdr *)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 hostlist_table */
  add_hostlist_table_data(hash, &ehdr->src, 0, TRUE, 1, pinfo->fd->pkt_len, &fddi_host_dissector_info, ENDPOINT_NONE);
  add_hostlist_table_data(hash, &ehdr->dst, 0, FALSE, 1, pinfo->fd->pkt_len, &fddi_host_dissector_info, ENDPOINT_NONE);

  return TAP_PACKET_REDRAW;
}

static gboolean
capture_fddi(const guchar *pd, int offset, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header)
{
  int fc;

  if (!BYTES_ARE_IN_FRAME(0, len, FDDI_HEADER_SIZE + FDDI_PADDING))
    return FALSE;

  offset = FDDI_PADDING + FDDI_HEADER_SIZE;

  fc = (int) pd[FDDI_P_FC+FDDI_PADDING];

  switch (fc) {

    /* From now, only 802.2 SNAP (Async. LCC frame) is supported */

    case FDDI_FC_LLC_ASYNC + 0  :
    case FDDI_FC_LLC_ASYNC + 1  :
    case FDDI_FC_LLC_ASYNC + 2  :
    case FDDI_FC_LLC_ASYNC + 3  :
    case FDDI_FC_LLC_ASYNC + 4  :
    case FDDI_FC_LLC_ASYNC + 5  :
    case FDDI_FC_LLC_ASYNC + 6  :
    case FDDI_FC_LLC_ASYNC + 7  :
    case FDDI_FC_LLC_ASYNC + 8  :
    case FDDI_FC_LLC_ASYNC + 9  :
    case FDDI_FC_LLC_ASYNC + 10 :
    case FDDI_FC_LLC_ASYNC + 11 :
    case FDDI_FC_LLC_ASYNC + 12 :
    case FDDI_FC_LLC_ASYNC + 13 :
    case FDDI_FC_LLC_ASYNC + 14 :
    case FDDI_FC_LLC_ASYNC + 15 :
      return call_capture_dissector(llc_cap_handle, pd, offset, len, cpinfo, pseudo_header);
  } /* fc */

  return FALSE;
} /* capture_fddi */

static const gchar *
fddifc_to_str(int fc)
{
  static gchar strbuf[128+1];

  switch (fc) {

  case FDDI_FC_VOID:                    /* Void frame */
    return "Void frame";

  case FDDI_FC_NRT:                     /* Nonrestricted token */
    return "Nonrestricted token";

  case FDDI_FC_RT:                      /* Restricted token */
    return "Restricted token";

  case FDDI_FC_SMT_INFO:                /* SMT Info */
    return "SMT info";

  case FDDI_FC_SMT_NSA:                 /* SMT Next station adrs */
    return "SMT Next station address";

  case FDDI_FC_MAC_BEACON:              /* MAC Beacon frame */
    return "MAC beacon";

  case FDDI_FC_MAC_CLAIM:               /* MAC Claim frame */
    return "MAC claim token";

  default:
    switch (fc & FDDI_FC_CLFF) {

    case FDDI_FC_MAC:
      g_snprintf(strbuf, sizeof(strbuf), "MAC frame, control %x", fc & FDDI_FC_ZZZZ);
      return strbuf;

    case FDDI_FC_SMT:
      g_snprintf(strbuf, sizeof(strbuf), "SMT frame, control %x", fc & FDDI_FC_ZZZZ);
      return strbuf;

    case FDDI_FC_LLC_ASYNC:
      if (fc & FDDI_FC_ASYNC_R)
        g_snprintf(strbuf, sizeof(strbuf), "Async LLC frame, control %x", fc & FDDI_FC_ZZZZ);
      else
        g_snprintf(strbuf, sizeof(strbuf), "Async LLC frame, priority %d",
                        fc & FDDI_FC_ASYNC_PRI);
      return strbuf;

    case FDDI_FC_LLC_SYNC:
      if (fc & FDDI_FC_ZZZZ) {
        g_snprintf(strbuf, sizeof(strbuf), "Sync LLC frame, control %x", fc & FDDI_FC_ZZZZ);
        return strbuf;
      } else
        return "Sync LLC frame";

    case FDDI_FC_IMP_ASYNC:
      g_snprintf(strbuf, sizeof(strbuf), "Implementor async frame, control %x",
                        fc & FDDI_FC_ZZZZ);
      return strbuf;

    case FDDI_FC_IMP_SYNC:
      g_snprintf(strbuf, sizeof(strbuf), "Implementor sync frame, control %x",
                        fc & FDDI_FC_ZZZZ);
      return strbuf;

    default:
      return "Unknown frame type";
    }
  }
}


static void
dissect_fddi(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
             gboolean bitswapped)
{
  proto_tree      *fh_tree     = NULL;
  proto_item      *ti, *hidden_item;
  const gchar     *fc_str;
  proto_tree      *fc_tree;
  guchar          *src = (guchar*)wmem_alloc(pinfo->pool, 6), *dst = (guchar*)wmem_alloc(pinfo->pool, 6);
  guchar           src_swapped[6], dst_swapped[6];
  tvbuff_t        *next_tvb;
  static fddi_hdr  fddihdrs[4];
  static int       fddihdr_num = 0;
  fddi_hdr        *fddihdr;

  fddihdr_num++;
  if (fddihdr_num >= 4) {
     fddihdr_num = 0;
  }
  fddihdr = &fddihdrs[fddihdr_num];

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

  fddihdr->fc = tvb_get_guint8(tvb, FDDI_P_FC + FDDI_PADDING);
  fc_str = fddifc_to_str(fddihdr->fc);

  col_add_str(pinfo->cinfo, COL_INFO, fc_str);

  if (tree) {
    ti = proto_tree_add_protocol_format(tree, proto_fddi, tvb, 0, FDDI_HEADER_SIZE+FDDI_PADDING,
                                        "Fiber Distributed Data Interface, %s", fc_str);
    fh_tree = proto_item_add_subtree(ti, ett_fddi);
    ti = proto_tree_add_uint_format_value(fh_tree, hf_fddi_fc, tvb, FDDI_P_FC + FDDI_PADDING, 1, fddihdr->fc,
        "0x%02x (%s)", fddihdr->fc, fc_str);
    fc_tree = proto_item_add_subtree(ti, ett_fddi_fc);
    proto_tree_add_uint(fc_tree, hf_fddi_fc_clf, tvb, FDDI_P_FC + FDDI_PADDING, 1, fddihdr->fc);
    switch ((fddihdr->fc) & FDDI_FC_CLFF) {

    case FDDI_FC_SMT:
      proto_tree_add_uint(fc_tree, hf_fddi_fc_smt_subtype, tvb, FDDI_P_FC + FDDI_PADDING, 1, fddihdr->fc);
      break;

    case FDDI_FC_MAC:
      if (fddihdr->fc != FDDI_FC_RT)
        proto_tree_add_uint(fc_tree, hf_fddi_fc_mac_subtype, tvb, FDDI_P_FC + FDDI_PADDING, 1, fddihdr->fc);
      break;

    case FDDI_FC_LLC_ASYNC:
      if (!((fddihdr->fc) & FDDI_FC_ASYNC_R))
        proto_tree_add_uint(fc_tree, hf_fddi_fc_prio, tvb, FDDI_P_FC + FDDI_PADDING, 1, fddihdr->fc);
      break;
    }
  }

  /* Extract the destination address, possibly bit-swapping it. */
  if (bitswapped)
    swap_mac_addr(dst, tvb, FDDI_P_DHOST + FDDI_PADDING);
  else
    tvb_memcpy(tvb, dst, FDDI_P_DHOST + FDDI_PADDING, 6);
  swap_mac_addr(dst_swapped, tvb, FDDI_P_DHOST + FDDI_PADDING);

  set_address(&pinfo->dl_dst, AT_ETHER, 6, dst);
  copy_address_shallow(&pinfo->dst, &pinfo->dl_dst);
  copy_address_shallow(&fddihdr->dst, &pinfo->dl_dst);

  if (fh_tree) {
    proto_tree_add_ether(fh_tree, hf_fddi_dst, tvb, FDDI_P_DHOST + FDDI_PADDING, 6, dst);
    hidden_item = proto_tree_add_ether(fh_tree, hf_fddi_addr, tvb, FDDI_P_DHOST + FDDI_PADDING, 6, dst);
    proto_item_set_hidden(hidden_item);

    /* hide some bit-swapped mac address fields in the proto_tree, just in case */
    hidden_item = proto_tree_add_ether(fh_tree, hf_fddi_dst, tvb, FDDI_P_DHOST + FDDI_PADDING, 6, dst_swapped);
    proto_item_set_hidden(hidden_item);
    hidden_item = proto_tree_add_ether(fh_tree, hf_fddi_addr, tvb, FDDI_P_DHOST + FDDI_PADDING, 6, dst_swapped);
    proto_item_set_hidden(hidden_item);
  }

  /* Extract the source address, possibly bit-swapping it. */
  if (bitswapped)
    swap_mac_addr(src, tvb, FDDI_P_SHOST + FDDI_PADDING);
  else
    tvb_memcpy(tvb, src, FDDI_P_SHOST + FDDI_PADDING, 6);
  swap_mac_addr(src_swapped, tvb, FDDI_P_SHOST + FDDI_PADDING);

  set_address(&pinfo->dl_src, AT_ETHER, 6, src);
  copy_address_shallow(&pinfo->src, &pinfo->dl_src);
  copy_address_shallow(&fddihdr->src, &pinfo->dl_src);

  if (fh_tree) {
    proto_tree_add_ether(fh_tree, hf_fddi_src, tvb, FDDI_P_SHOST + FDDI_PADDING, 6, src);
    hidden_item = proto_tree_add_ether(fh_tree, hf_fddi_addr, tvb, FDDI_P_SHOST + FDDI_PADDING, 6, src);
    proto_item_set_hidden(hidden_item);

    /* hide some bit-swapped mac address fields in the proto_tree, just in case */
    hidden_item = proto_tree_add_ether(fh_tree, hf_fddi_src, tvb, FDDI_P_SHOST + FDDI_PADDING, 6, src_swapped);
    proto_item_set_hidden(hidden_item);
    hidden_item = proto_tree_add_ether(fh_tree, hf_fddi_addr, tvb, FDDI_P_SHOST + FDDI_PADDING, 6, src_swapped);
    proto_item_set_hidden(hidden_item);
  }

  next_tvb = tvb_new_subset_remaining(tvb, FDDI_HEADER_SIZE + FDDI_PADDING);


  tap_queue_packet(fddi_tap, pinfo, fddihdr);

  switch (fddihdr->fc) {

    /* From now, only 802.2 SNAP (Async. LCC frame) is supported */

    case FDDI_FC_LLC_ASYNC + 0  :
    case FDDI_FC_LLC_ASYNC + 1  :
    case FDDI_FC_LLC_ASYNC + 2  :
    case FDDI_FC_LLC_ASYNC + 3  :
    case FDDI_FC_LLC_ASYNC + 4  :
    case FDDI_FC_LLC_ASYNC + 5  :
    case FDDI_FC_LLC_ASYNC + 6  :
    case FDDI_FC_LLC_ASYNC + 7  :
    case FDDI_FC_LLC_ASYNC + 8  :
    case FDDI_FC_LLC_ASYNC + 9  :
    case FDDI_FC_LLC_ASYNC + 10 :
    case FDDI_FC_LLC_ASYNC + 11 :
    case FDDI_FC_LLC_ASYNC + 12 :
    case FDDI_FC_LLC_ASYNC + 13 :
    case FDDI_FC_LLC_ASYNC + 14 :
    case FDDI_FC_LLC_ASYNC + 15 :
      call_dissector(llc_handle, next_tvb, pinfo, tree);
      return;

    default :
      call_data_dissector(next_tvb, pinfo, tree);
      return;

  } /* fc */
} /* dissect_fddi */


static int
dissect_fddi_bitswapped(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
  dissect_fddi(tvb, pinfo, tree, TRUE);
  return tvb_captured_length(tvb);
}

static int
dissect_fddi_not_bitswapped(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
  dissect_fddi(tvb, pinfo, tree, FALSE);
  return tvb_captured_length(tvb);
}

void
proto_register_fddi(void)
{
  static hf_register_info hf[] = {

    { &hf_fddi_fc,
      { "Frame Control", "fddi.fc", FT_UINT8, BASE_HEX, NULL, 0x0,
        NULL, HFILL }},

    { &hf_fddi_fc_clf,
      { "Class/Length/Format", "fddi.fc.clf", FT_UINT8, BASE_HEX, VALS(clf_vals), FDDI_FC_CLFF,
        NULL, HFILL }},

    { &hf_fddi_fc_prio,
      { "Priority", "fddi.fc.prio", FT_UINT8, BASE_DEC, NULL, FDDI_FC_ASYNC_PRI,
        NULL, HFILL }},

    { &hf_fddi_fc_smt_subtype,
      { "SMT Subtype", "fddi.fc.smt_subtype", FT_UINT8, BASE_DEC, VALS(smt_subtype_vals), FDDI_FC_ZZZZ,
        NULL, HFILL }},

    { &hf_fddi_fc_mac_subtype,
      { "MAC Subtype", "fddi.fc.mac_subtype", FT_UINT8, BASE_DEC, VALS(mac_subtype_vals), FDDI_FC_ZZZZ,
        NULL, HFILL }},

    { &hf_fddi_dst,
      { "Destination", "fddi.dst", FT_ETHER, BASE_NONE, NULL, 0x0,
        "Destination Hardware Address", HFILL }},

    { &hf_fddi_src,
      { "Source", "fddi.src", FT_ETHER, BASE_NONE, NULL, 0x0,
        NULL, HFILL }},

    { &hf_fddi_addr,
      { "Source or Destination Address", "fddi.addr", FT_ETHER, BASE_NONE, NULL, 0x0,
        "Source or Destination Hardware Address", HFILL }},

  };
  static gint *ett[] = {
    &ett_fddi,
    &ett_fddi_fc,
  };

  module_t *fddi_module;

  proto_fddi = proto_register_protocol("Fiber Distributed Data Interface",
                                       "FDDI", "fddi");
  proto_register_field_array(proto_fddi, hf, array_length(hf));
  proto_register_subtree_array(ett, array_length(ett));

  /*
   * Called from various dissectors for encapsulated FDDI frames.
   * We assume the MAC addresses in them aren't bitswapped.
   */
  fddi_handle = register_dissector("fddi", dissect_fddi_not_bitswapped, proto_fddi);

  /*
   * Here, we assume they are bitswapped.
   */
  fddi_bitswapped_handle = register_dissector("fddi_bitswapped", dissect_fddi_bitswapped, proto_fddi);

  fddi_module = prefs_register_protocol(proto_fddi, NULL);
  prefs_register_bool_preference(fddi_module, "padding",
                                 "Add 3-byte padding to all FDDI packets",
                                 "Whether the FDDI dissector should add 3-byte padding to all "
                                 "captured FDDI packets (useful with e.g. Tru64 UNIX tcpdump)",
                                 &fddi_padding);

  fddi_tap = register_tap("fddi");
  register_conversation_table(proto_fddi, TRUE, fddi_conversation_packet, fddi_hostlist_packet);
}

void
proto_reg_handoff_fddi(void)
{
  capture_dissector_handle_t fddi_cap_handle;

  /*
   * Get a handle for the LLC dissector.
   */
  llc_handle = find_dissector_add_dependency("llc", proto_fddi);

  dissector_add_uint("wtap_encap", WTAP_ENCAP_FDDI, fddi_handle);
  dissector_add_uint("wtap_encap", WTAP_ENCAP_FDDI_BITSWAPPED,
                     fddi_bitswapped_handle);
  dissector_add_uint("sflow_245.header_protocol", SFLOW_245_HEADER_FDDI,
                     fddi_handle);

  fddi_cap_handle = create_capture_dissector_handle(capture_fddi, proto_fddi);
  capture_dissector_add_uint("wtap_encap", WTAP_ENCAP_FDDI, fddi_cap_handle);
  capture_dissector_add_uint("wtap_encap", WTAP_ENCAP_FDDI_BITSWAPPED, fddi_cap_handle);

  llc_cap_handle = find_capture_dissector("llc");
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local Variables:
 * c-basic-offset: 2
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * ex: set shiftwidth=2 tabstop=8 expandtab:
 * :indentSize=2:tabSize=8:noTabs=true:
 */
