[catacomb] / symm / strobe.c

/* -*-c-*-
 *
 * The STROBE protocol framework
 *
 * (c) 2018 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Library General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Catacomb is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb.  If not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA.
 */

/*----- Header files ------------------------------------------------------*/

#include <assert.h>
#include <ctype.h>
#include <string.h>

#include <mLib/buf.h>

#include "keccak1600.h"
#include "strobe.h"

/*----- Magic constants ---------------------------------------------------*/

#define DDATA 0x04
#define DRATE 0x80

/*----- Utilities ---------------------------------------------------------*/

/* --- @crank@ --- *
 *
 * Arguments:	@strobe_ctx *ctx@ = pointer to context block to initialize
 *
 * Returns:	---
 *
 * Use:		Cycle the Keccak-p[1600, n] duplex function.
 */

static void crank(strobe_ctx *ctx)
{
  kludge64 t[25];
  octet *p;
  unsigned i;

  /* Ensure that we've not overstepped the rate bound. */
  assert(ctx->n <= ctx->r - 2);

  /* Apply the cSHAKE and rate padding. */
  ctx->buf[ctx->n] ^= ctx->n0;
  ctx->buf[ctx->n + 1] ^= DDATA;
  ctx->buf[ctx->r - 1] ^= DRATE;

  /* Cycle the sponge. */
  for (i = 0, p = ctx->buf; i < ctx->r/8; i++)
    { LOAD64_L_(t[i], p); p += 8; }
  keccak1600_set(&ctx->k, t, ctx->r/8);
  keccak1600_p(&ctx->k, &ctx->k, 24);
  keccak1600_extract(&ctx->k, t, ctx->r/8);
  for (i = 0, p = ctx->buf; i < ctx->r/8; i++)
    { STORE64_L_(p, t[i]); p += 8; }

  /* Restart at the beginning of the buffer, and note this as a
   * continuation.
   */
  ctx->n = ctx->n0 = 0;
}

/* --- @xorbuf@ --- *
 *
 * Arguments:	@octet *z@ = pointer to output buffer
 *		@const octet *x, *y@ = pointer to input buffers
 *		@size_t sz@ = common buffer length
 *
 * Returns:	---
 *
 * Use:		Store the bytewise XOR of the buffers @x@ and @y@ in @z@.
 *		The @x@ and @y@ may be equal, but otherwise the buffers must
 *		not overlap.
 */

static void xorbuf(octet *z, const octet *x, const octet *y, size_t sz)
  { size_t i; for (i = 0; i < sz; i++) *z++ = *x++ ^ *y++; }

/* --- @nonzerop@ --- *
 *
 * Arguments:	@const octet *x@ = pointer to input buffer
 *		@size_t sz@ = buffer length
 *
 * Returns:	---
 *
 * Use:		If any byte of @x@ is nonzero, then return a nonzero value
 *		between 1 and 255 inclusive; otherwise return zero.
 */

static unsigned nonzerop(const octet *x, size_t sz)
{
  unsigned z = 0;
  size_t i;

  for (i = 0; i < sz; i++) z |= *x++;
  return (z);
}

/* --- @unequalp@ --- *
 *
 * Arguments:	@const octet *x, *y@ = pointer to input buffers
 *		@size_t sz@ = common buffer length
 *
 * Returns:	---
 *
 * Use:		If any respective bytes of @x@ and @y@ are unequal, then
 *		return a nonzero value between 1 and 255 inclusive; otherwise
 *		return zero.
 */

static unsigned unequalp(const octet *x, const octet *y, size_t sz)
{
  unsigned z = 0;
  size_t i;

  for (i = 0; i < sz; i++) z |= *x++ ^ *y++;
  return (z);
}

/* --- @process_buffer@ --- *
 *
 * Arguments:	@strobe_ctx *ctx@ = pointer to context block
 *		@const octet *p@ = pointer to input buffer
 *		@octet *q@ = pointer to output buffer
 *		@size_t sz@ = common buffer length
 *
 * Returns:	---
 *
 * Use:		Process a portion of a STROBE input small enough to be
 *		satisfied from the internal buffer.
 */

static void process_buffer(strobe_ctx *ctx,
			   const octet *p, octet *q, size_t sz)
{
  octet *b = ctx->buf + ctx->n;
  unsigned z = 0;

  if (!(ctx->f&STRBF_CRYPTO)) {
    /* No crypto to do.  The `output' would be equal to the input, so that's
     * rather uninteresting (and, indeed, forbidden).  If there's input, then
     * mix it into the state.
     */

    if (p && (ctx->f&STRBF_VRFOUT)) z |= nonzerop(p, sz);
    if (p) xorbuf(b, b, p, sz);
  } else if (!(ctx->f&STRBF_MIXOUT)) {
    /* Mix the input into the sponge state.  That means that the new state
     * will be equal to the output.
     */

    if (p) xorbuf(b, b, p, sz);
    if (ctx->f&STRBF_VRFOUT) z |= nonzerop(b, sz);
    if (q) memcpy(q, b, sz);
  } else if (p) {
    /* Mix the output into the sponge state, so the new state will in fact be
     * equal to the input.  If the input and output buffers are equal then we
     * have a dance to do.
     */

    if (!q) {
      if (ctx->f&STRBF_VRFOUT) z |= unequalp(p, b, sz);
      memcpy(b, p, sz);
    } else {
      xorbuf(q, p, b, sz);
      if (q != p) memcpy(b, p, sz);
      else xorbuf(b, b, q, sz);
      if (ctx->f&STRBF_VRFOUT) z |= nonzerop(q, sz);
    }
  } else {
    /* As above, only the input is hardwired to zero.  That means that we
     * copy state bytes to the output (if any), and just clobber the state
     * when we're done.
     */

    if (q) memcpy(q, b, sz);
    memset(b, 0, sz);
  }

  /* Set the @STRBF_NZERO@ flag if @z@ is nonzero.  If @z@ is zero then
   * subtracting one will set all of its bits, so, in particular, bits
   * 8--15.  Otherwise, @z@ is between 1 and 255, so bits 8--15 are clear and
   * will remain so when we subtract one.
   */
  if (ctx->f&STRBF_VRFOUT) ctx->f |= ((z - 1)&STRBF_NZERO) ^ STRBF_NZERO;

  /* Update the buffer cursor. */
  ctx->n += sz;
}

/*----- Interface ---------------------------------------------------------*/

/* --- @strobe_init@ --- *
 *
 * Arguments:	@strobe_ctx *ctx@ = pointer to context block to initialize
 *		@unsigned lambda@ = security parameter, in bits (must be a
 *			multiple of 32)
 *
 * Returns:	---
 *
 * Use:		Initialize a STROBE context for use.
 */

void strobe_init(strobe_ctx *ctx, unsigned lambda)
{
  const char v[] = "STROBEv1.0.2";
  kludge64 t[25];
  octet *p;
  buf b;
  unsigned n, i;

  /* Check the security parameter. */
  assert(lambda%32 == 0); assert(lambda <= 704);
  ctx->r = (1600 - 2*lambda)/8;

  /* Set up the initial cSHAKE framing. */
  buf_init(&b, ctx->buf, ctx->r);
  buf_putu8(&b, 1); buf_putu8(&b, ctx->r);
  buf_putu8(&b, 1); buf_putu8(&b, 0);
  buf_putu8(&b, 1); buf_putu8(&b, 8*(sizeof(v) - 1));
  buf_put(&b, v, sizeof(v) - 1);
  assert(BOK(&b));
  n = BLEN(&b); if (n%8) memset(ctx->buf + n, 0, 8 - n%8);

  /* Cycle the sponge once initially, and get the first output buffer. */
  keccak1600_init(&ctx->k);
  for (i = 0, p = ctx->buf; i < (n + 7)/8; i++)
    { LOAD64_L_(t[i], p); p += 8; }
  keccak1600_set(&ctx->k, t, (n + 7)/8);
  keccak1600_p(&ctx->k, &ctx->k, 24);
  keccak1600_extract(&ctx->k, t, ctx->r/8);
  for (i = 0, p = ctx->buf; i < ctx->r/8; i++)
    { STORE64_L_(p, t[i]); p += 8; }

  /* Initialize the other parts of the state. */
  ctx->n = ctx->n0 = 0; ctx->f = 0;
}

/* --- @strobe_begin@ --- *
 *
 * Arguments:	@strobe_ctx *ctx@ = pointer to context block
 *		@unsigned op@ = bitmask of flags
 *
 * Returns:	---
 *
 * Use:		Begin a STROBE operation.  The flags determine the behaviour
 *		of the @strobe_process@ and @strobe_done@ functions.
 *
 *		  * The @I@ bit determines the primary direction of data
 *		    movement.  If it's clear, data comes from the application
 *		    into STROBE.  If it's set, data comes from STROBE towards
 *		    the application.
 *
 *		  * The @C@ bit activates cryptographic processing.  If it's
 *		    clear, then the input and output data would be equal, so
 *		    @dest@ must be null.  If it's set, then input data is
 *		    XORed with the keystream on its way to the output.
 *
 *		  * The @A@ bit determines whether the application is
 *		    engaged.  If it's set, then the input or output buffer
 *		    (according to whether @I@ is clear or set, respectively)
 *		    holds the application data.  If it's clear, and @I@ is
 *		    clear, then zero bytes are fed in; if @I@ is set, then
 *		    the output is compared with zero, and @strobe_done@
 *		    reports the outcome of this comparison.
 *
 *		  * The @T@ bit determines whether the transport is engaged.
 *		    If it's set, then the input or output buffer (according
 *		    to whether @I@ is set or clear, respectively) holds
 *		    transport data.  If it's clear, and @I@ is set, then zero
 *		    bytes are fed in; if @I@ is clear, then the output is
 *		    discarded.
 *
 *		  * The @M@ bit marks the data as metadata, but has no other
 *		    effect.
 */

void strobe_begin(strobe_ctx *ctx, unsigned op)
{
  /* Preliminary checking.  We shouldn't have an operation underway, and the
   * operation shouldn't have reserved bits set.
   */
  assert(!(ctx->f&STRBF_ACTIVE)); assert(!(op&~STRBF_VALIDMASK));

  /* Reset our operation state. */
  ctx->f &= STRBF_STMASK;

  /* Operation framing.  Chain back to the start of the previous frame and
   * write the new operation code.  Set the sticky asymmetry bit here if
   * necessary.
   */
  ctx->buf[ctx->n++] ^= ctx->n0; ctx->n0 = ctx->n;
  if (ctx->n >= ctx->r - 2) crank(ctx);
  if (!(op&STRBF_T))
    ctx->buf[ctx->n++] ^= U8(op);
  else {
    if (!(ctx->f&STRBF_INIT)) ctx->f |= STRBF_INIT | (op&STRBF_I);
    ctx->buf[ctx->n++] ^= U8(op ^ ctx->f);
  }
  if (ctx->n >= ctx->r - 2 || (op&STRBF_C)) crank(ctx);

  /* The operation is now underway. */
  ctx->f |= STRBF_ACTIVE;

  /* Determine whether we expect input and/or output. */
  if (op&(op&STRBF_I ? STRBF_T : STRBF_A))
    ctx->f |= STRBF_WANTIN;
  if ((op&STRBF_C) && op&(op&STRBF_I ? STRBF_A : STRBF_T))
    ctx->f |= STRBF_WANTOUT;

  /* Determine whether the keystream is engaged, and how it fits in. */
  if (op&STRBF_C) {
    ctx->f |= STRBF_CRYPTO;
    if ((op&(STRBF_I | STRBF_T)) != STRBF_T) ctx->f |= STRBF_MIXOUT;
  }

  /* Determine whether the output is supposed to be all-bytes-zero. */
  if ((op&(STRBF_I | STRBF_A | STRBF_T)) == (STRBF_I | STRBF_T))
    ctx->f |= STRBF_VRFOUT;

  /* The operation is now underway. */
  ctx->f |= STRBF_ACTIVE;
}

/* --- @strobe_process@ --- *
 *
 * Arguments:	@strobe_ctx *ctx@ = pointer to context block
 *		@const void *src@ = pointer to input data, or null
 *		@void *dest@ = pointer to output data, or null
 *		@size_t sz@ = common buffer length
 *
 * Returns:	---
 *
 * Use:		Process data through the active STROBE operation.  The exact
 *		behaviour depends on the flags passed to @strobe_begin@; see
 *		that function for details.  If @src@ is null, then the
 *		behaviour is as if the input consists of @sz@ zero bytes.  If
 *		@dest@ in null, then the output is discarded.
 */

void strobe_process(strobe_ctx *ctx, const void *src, void *dest, size_t sz)
{
  const octet *p = src; octet *q = dest;
  unsigned spare;

  /* Make sure that things are set up properly. */
  assert(ctx->f&STRBF_ACTIVE);
  if (!(ctx->f&STRBF_WANTIN)) assert(!src);
  if (!(ctx->f&STRBF_WANTOUT)) assert(!dest);

  /* Work through the input. */
  spare = ctx->r - ctx->n - 2;
  if (sz < spare)
    { process_buffer(ctx, p, q, sz); return; }
  if (ctx->n) {
    process_buffer(ctx, p, q, spare); crank(ctx);
    if (p) { p += spare; }
    if (q) { q += spare; }
    sz -= spare;
  }

  while (sz >= ctx->r - 2) {
    process_buffer(ctx, p, q, ctx->r - 2); crank(ctx);
    if (p) { p += ctx->r - 2; }
    if (q) { q += ctx->r - 2; }
    sz -= ctx->r - 2;
  }
  if (sz) process_buffer(ctx, p, q, sz);
}

/* --- @strobe_done@ --- *
 *
 * Arguments:	@strobe_ctx *ctx@ = pointer to context block
 *
 * Returns:	Zero on success; @-1@ on verification failure (if @I@ and @T@
 *			are set and @A@ is clear)
 *
 * Use:		Concludes a STROBE operation, returning the result.
 */

int strobe_done(strobe_ctx *ctx)
{
  assert(ctx->f&STRBF_ACTIVE); ctx->f &= ~STRBF_ACTIVE;
  if (ctx->f&STRBF_VRFOUT) return (-(int)((ctx->f/STRBF_NZERO)&1u));
  else return (0);
}

/* --- @strobe_key@, @strobe_ad@, @strobe_@prf@, @strobe_clrout@,
 *     @strobe_clrin@, @strobe_encout@, @strobe_encin@, @strobe_macout@,
 *     @strobe_macin@, @strobe_ratchet@ --- *
 *
 * Arguments:	@strobe_ctx *ctx@ = pointer to context block
 *
 * Returns:	@strobe_macin@ returns zero on success, or @-1@ on
 *			verification failure
 *
 * Use:		Perform a STROBE operation on a single buffer.
 */

static int op(strobe_ctx *ctx, unsigned f0, unsigned f1,
	      const void *src, void *dest, size_t sz)
{
  assert(!(f1&~STRBF_M));

  strobe_begin(ctx, f0 | f1);
  strobe_process(ctx, src, dest, sz);
  return (strobe_done(ctx));
}

void strobe_key(strobe_ctx *ctx, unsigned f, const void *k, size_t sz)
  { op(ctx, STROBE_KEY, f, k, 0, sz); }

void strobe_ad(strobe_ctx *ctx, unsigned f, const void *h, size_t sz)
  { op(ctx, STROBE_AD, f, h, 0, sz); }

void strobe_prf(strobe_ctx *ctx, unsigned f, void *t, size_t sz)
  { op(ctx, STROBE_PRF, f, 0, t, sz); }

void strobe_clrout(strobe_ctx *ctx, unsigned f, const void *m, size_t sz)
  { op(ctx, STROBE_CLROUT, f, m, 0, sz); }

void strobe_clrin(strobe_ctx *ctx, unsigned f, const void *m, size_t sz)
  { op(ctx, STROBE_CLRIN, f, m, 0, sz); }

void strobe_encout(strobe_ctx *ctx, unsigned f,
		   const void *m, void *c, size_t sz)
  { op(ctx, STROBE_ENCOUT, f, m, c, sz); }

void strobe_encin(strobe_ctx *ctx, unsigned f,
		  const void *c, void *m, size_t sz)
  { op(ctx, STROBE_ENCIN, f, c, m, sz); }

void strobe_macout(strobe_ctx *ctx, unsigned f, void *t, size_t sz)
  { op(ctx, STROBE_MACOUT, f, 0, t, sz); }

int strobe_macin(strobe_ctx *ctx, unsigned f, const void *t, size_t sz)
  { return (op(ctx, STROBE_MACIN, f, t, 0, sz)); }

void strobe_ratchet(strobe_ctx *ctx, unsigned f, size_t sz)
  { op(ctx, STROBE_RATCHET, f, 0, 0, sz); }

/*----- Test rig ----------------------------------------------------------*/

#ifdef TEST_RIG

#include <stdlib.h>
#include <string.h>

#include <mLib/hex.h>
#include <mLib/macros.h>
#include <mLib/testrig.h>

#define NSTATE 16

static strobe_ctx states[NSTATE];

static void dump(int rc, char win, const void *p, size_t sz)
{
  dstr d = DSTR_INIT;
  const char *q = p;
  size_t i;
  codec *hex;
  int printable;

  if (!p) {
    if (!rc) putchar(win);
    else putchar('-');
  } else {
    for (i = 0, printable = 1; i < sz; i++)
      if (!ISPRINT(q[i])) { printable = 0; break; }
    if (printable)
      printf("`%s'", q);
    else {
      hex = hex_class.encoder(CDCF_LOWERC, 0, 0);
      hex->ops->code(hex, p, sz, &d);
      dstr_write(&d, stdout);
      hex->ops->destroy(hex);
    }
  }
  dstr_destroy(&d);
  putchar('\n');
}

typedef int opfunc(strobe_ctx *, unsigned, const void *, void *, size_t);

static int op_init(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_init(ctx, sz); return (0); }

static int op_copy(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { *ctx = states[sz]; return (0); }

static int op_begin(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_begin(ctx, f); return (0); }

static int op_process(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_process(ctx, p, q, sz); return (0); }

static int op_done(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { return (strobe_done(ctx)); }

static int op_key(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_key(ctx, f, p, sz); return (0); }

static int op_ad(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_ad(ctx, f, p, sz); return (0); }

static int op_prf(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_prf(ctx, f, q, sz); return (0); }

static int op_clrout(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_clrout(ctx, f, p, sz); return (0); }

static int op_clrin(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_clrin(ctx, f, p, sz); return (0); }

static int op_encout(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_encout(ctx, f, p, q, sz); return (0); }

static int op_encin(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_encin(ctx, f, p, q, sz); return (0); }

static int op_macout(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { strobe_macout(ctx, f, q, sz); return (0); }

static int op_macin(strobe_ctx *ctx, unsigned f,
		   const void *p, void *q, size_t sz)
  { return (strobe_macin(ctx, f, p, sz)); }

static int op_ratchet(strobe_ctx *ctx, unsigned f,
		      const void *p, void *q, size_t sz)
  { strobe_ratchet(ctx, f, sz); return (0); }

static const struct optab {
  const char *name;
  opfunc *op;
} optab[] = {
#define OP(op) { #op, op_##op }
  OP(init), OP(copy),
  OP(begin), OP(process), OP(done),
  OP(key), OP(ad), OP(prf),
  OP(clrout), OP(clrin),
  OP(encout), OP(encin),
  OP(macout), OP(macin),
  OP(ratchet),
  { 0 }
#undef OP
};

static int verify(dstr v[])
{
  int r;
  strobe_ctx *ctx;
  const char *p;
  char *q;
  const struct optab *op;
  dstr d0 = DSTR_INIT, d1 = DSTR_INIT;
  codec *hex;
  unsigned f;
  const void *src, *destref;
  void *dest;
  size_t sz;
  int rc, rcref;
  int ok;

  /* First, get the register number. */
  r = *(int *)v[0].buf; ctx = &states[r];

  /* Next job is to parse the command and flags. */
  q = v[1].buf; p = q; q += strcspn(q, "/"); if (*q) *q++ = 0;
  for (op = optab; op->name; op++)
    if (STRCMP(op->name, ==, p)) goto found_op;
  abort();
found_op:

  f = 0;
  for (p = q; *p; p++) {
    switch (*p) {
      case 'I': f |= STRBF_I; break;
      case 'C': f |= STRBF_C; break;
      case 'A': f |= STRBF_A; break;
      case 'T': f |= STRBF_T; break;
      case 'M': f |= STRBF_M; break;
      default: abort();
    }
  }

  /* Convert the source parameter. */
  p = v[2].buf;
  if (*p == '*')
    { src = 0; sz = strtoul(p + 1, 0, 0); }
  else if (*p == '=')
    { src = p + 1; sz = v[2].len - 1; }
  else if (*p == '!') {
    hex = hex_class.decoder(CDCF_IGNCASE);
    rc = hex->ops->code(hex, p + 1, v[2].len - 1, &d0); assert(!rc);
    src = d0.buf; sz = d0.len;
    hex->ops->destroy(hex);
  } else
    abort();

  /* Convert the destination parameter. */
  p = v[3].buf;
  if (*p == '+')
    { destref = 0; rcref = 0; assert(v[3].len == 1); }
  else if (*p == '-')
    { destref = 0; rcref = -1; assert(v[3].len == 1); }
  else if (*p == '=')
    { destref = p + 1; assert(sz == v[3].len - 1); rcref = 0; }
  else if (*p == '!') {
    hex = hex_class.decoder(CDCF_IGNCASE);
    rc = hex->ops->code(hex, p + 1, v[3].len - 1, &d1); assert(!rc);
    destref = d1.buf; assert(sz == d1.len);
    hex->ops->destroy(hex);
    rcref = 0;
  } else
    abort();
  if (!destref) dest = 0;
  else dest = xmalloc(sz);

  /* Do the operation. */
  rc = op->op(ctx, f, src, dest, sz);

  /* Check we got the right answer. */
  ok = (rc == rcref && (!destref || MEMCMP(dest, ==, destref, sz)));
  if (!ok) {
    printf("failed test\n");
    printf("	    state = %d\n", r);
    printf("	operation = %s%s%s%s%s%s%s\n",
	   op->name,
	   f ? "/" : "",
	   f&STRBF_I ? "I" : "",
	   f&STRBF_A ? "A" : "",
	   f&STRBF_C ? "C" : "",
	   f&STRBF_T ? "T" : "",
	   f&STRBF_M ? "M" : "");
    printf("	    input = "); dump(0, '*', src, sz);
    printf("	 computed = "); dump(rc, '+', dest, sz);
    printf("	 expected = "); dump(rcref, '+', destref, sz);
  }

  dstr_destroy(&d0);
  dstr_destroy(&d1);
  free(dest);
  return (ok);
}

static test_chunk tests[] = {
  { "strobe", verify,
    { &type_int, &type_string, &type_string, &type_string, 0 } },
  { 0, 0, { 0 } }
};

int main(int argc, char *argv[])
{
  test_run(argc, argv, tests, SRCDIR "/t/strobe");
  return (0);
}

#endif

/*----- That's all, folks -------------------------------------------------*/