/*++ /* NAME /* rand_sleep 3 /* SUMMARY /* sleep for randomized interval /* SYNOPSIS /* #include <iostuff.h> /* /* void rand_sleep(delay, variation) /* unsigned delay; /* unsigned variation; /* DESCRIPTION /* rand_sleep() blocks the current process for an amount of time /* pseudo-randomly chosen from the interval (delay +- variation/2). /* /* Arguments: /* .IP delay /* Time to sleep in microseconds. /* .IP variation /* Variation in microseconds; must not be larger than delay. /* DIAGNOSTICS /* Panic: interface violation. All system call errors are fatal. /* LICENSE /* .ad /* .fi /* The Secure Mailer license must be distributed with this software. /* AUTHOR(S) /* Wietse Venema /* IBM T.J. Watson Research /* P.O. Box 704 /* Yorktown Heights, NY 10598, USA /*--*/ /* System library. */ #include <sys_defs.h> #include <stdlib.h> #include <unistd.h> #include <time.h> /* Utility library. */ #include <msg.h> #include <myrand.h> #include <iostuff.h> /* rand_sleep - block for random time */ void rand_sleep(unsigned delay, unsigned variation) { const char *myname = "rand_sleep"; unsigned usec; /* * Sanity checks. */ if (delay == 0) msg_panic("%s: bad delay %d", myname, delay); if (variation > delay) msg_panic("%s: bad variation %d", myname, variation); /* * Use the semi-crappy random number generator. */ usec = (delay - variation / 2) + variation * (double) myrand() / RAND_MAX; doze(usec); } #ifdef TEST #include <msg_vstream.h> int main(int argc, char **argv) { int delay; int variation; msg_vstream_init(argv[0], VSTREAM_ERR); if (argc != 3) msg_fatal("usage: %s delay variation", argv[0]); if ((delay = atoi(argv[1])) <= 0) msg_fatal("bad delay: %s", argv[1]); if ((variation = atoi(argv[2])) < 0) msg_fatal("bad variation: %s", argv[2]); rand_sleep(delay * 1000000, variation * 1000000); exit(0); } #endif