-/* $Id: entropy_disk.c,v 1.4 2006/09/07 08:08:13 mmondor Exp $ */
+/* $Id: entropy_disk.c,v 1.5 2006/09/21 20:11:16 mmondor Exp $ */
/*
- * Copyright (c) 2006, Matthew Mondor
- * ALL RIGHTS RESERVED.
+ * Copyright (c) 2006 Pulsar-Zone, Reg.
+ * All rights reserved.
+ *
+ * Written by Matthew Mondor for Pulsar-Zone, Reg.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed for the NetBSD Project by
+ * Pulsar-Zone, Reg.
+ * 4. The name of Pulsar-Zone, Reg. may not be used to endorse
+ * or promote products derived from this software without specific prior
+ * written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY PULSAR-ZONE, REG ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL PULSAR-ZONE, REG
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
*/
/*
* XXX Possibly add an option to tell the daemon to automatially exit after a
* certain number of seconds or minutes elapsed. We would use setitimer(2)
* to receive a SIGALRM, acting the same as for SIGTERM upon its reception.
+ *
+ * XXX Make lseek(2)/read(2) errors silent via compile time option to not
+ * disclose any information in case of disk problems for a final version of
+ * this program.
*/
#include <sys/mman.h>
* Minimum block size to read (could be disk dependent but it doesn't matter
* much for this task.
*/
-#define BLOCK_SIZE 8192
+#define BLOCK_SIZE 16384
/*
* Maximum number of BLOCK_SIZE blocks to read in a single read(2)
*/
#define BLOCK_MULTIPLE 16
/*
* Minimum and maximum number of reads to perform in a single direction before
- * switching direction
+ * switching direction. If these are too low the disk head thrashing could be
+ * excessive.
+ */
+#define DIRECTION_MIN 256
+#define DIRECTION_MAX 4096
+/*
+ * Minimum and maximum reseeding of PRNG from urandom(4) frequency (in reads).
+ * If we set these this too low, the entropy we're trying to accumulate in
+ * rnd(4) is sucked out as we create it, causing us to loop indefinitely for
+ * nothing.
*/
-#define DIRECTION_MIN 64
-#define DIRECTION_MAX 2048
+#define RESEED_MIN 32
+#define RESEED_MAX 256
enum direction {
DIR_FORWARD = 0,
}
srandom(seed);
- reseed = random() % 20;
+ reseed = RESEED_MIN + (random() % (RESEED_MAX - RESEED_MIN));
return 0;
"read(/dev/urandom): %s\n", strerror(errno));
}
srandom(seed);
- reseed = random() % 20;
+ reseed = RESEED_MIN + (random() % (RESEED_MAX - RESEED_MIN));
}
}
Repositories / mmondor.git / commitdiff