actube/src/cw/cw_rand.c

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/*
This file is part of libcapwap.
libcapwap is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
libcapwap 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with Foobar. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "rand.h"
#include "log.h"
char *cw_rand_dev = "/dev/random";
int cw_rand_r(uint8_t * dst, int len)
{
int rf;
int l;
rf = open(cw_rand_dev, O_RDONLY | O_NONBLOCK);
if (rf < 0) {
cw_log(LOG_ERR, "Can't open %s: %s", cw_rand_dev, strerror(errno));
return 0;
}
l = read(rf, dst, len);
close(rf);
if ((l < 0) && (errno != EAGAIN)) {
cw_log(LOG_ERR, "Cant read from %s: %s", cw_rand_dev, strerror(errno));
return 0;
}
return l;
}
/**
* Generate random bytes
* @param dst Destination where to store random bytes
* @param len Number of bytes to generate
* @return Number of generated bytes
*/
int cw_rand(uint8_t * dst, int len)
{
static uint32_t rinit = 0;
int i;
if (!rinit) {
int l = cw_rand_r((uint8_t *) (&rinit), sizeof(uint32_t));
if (l < sizeof(uint32_t)) {
cw_log(LOG_WARNING,
"Can't read enough bytes from %s. Using time to init rand instead.",
cw_rand_dev);
rinit = time(NULL);
}
srand(rinit);
}
for (i = 0; i < len; i++) {
dst[i] = rand();
}
return len;
}